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PRINCETON,  N.  J.  . 


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Digitized  by  the  Internet  Archive 
in  2018  with  funding  from 
Princeton  Theological  Seminary  Library 


https://archive.org/details/reportofcommitte00amer_13 


PSYCHOLOGICAL  REVIEW  PUBLICATIONS 


Vol.  XIII 
No.  I 


December  1910 
Whole  No.  53 


THE 

Psychological  Monographs 


EDITED  BY 

JAMES  R.  ANGELL,  University  or  Chicago 
HOWARD  C.  WARREN,  Princeton  University  {Index) 

JOHN  B.  WATSON,  Johns  Hopkins  University  {Review) 
ARTHUR  H.  PIERCE,  Smith  College  {Bulletin) 


Report  of  the  Committee  of  the  American  Psycho¬ 
logical  Association  on  the  Standardizing  of  Proced¬ 
ure  in  Experimental  Tests. 

Committee : 

Charles  Hubbard  Judd 
Walter  B.  Pillsbury 
Carl  E.  Seashore 
Robert  S.  Woodworth 
James  R.  Angell,  Chairman 

Published  by  the  Association. 


THE  REVIEW  PUBLISHING  COMPANY 
41  NORTH  QUEEN  ST.,  LANCASTER,  PA. 
AND  BALTIMORE,  MD. 


WILLIAMS 


A  WILKINS  COMPANY 
BALTIMORE 


CONTENTS 


Preface,  by  the  Chairman  of  the  Committee,  James  R.  AngelL.  i 

I.  Methods  for  the  Determination  of  the  Intensity  of 

Sound,  W.  B.  Pillsbury .  5 

II.  The  Measurement  of  Pitch  Discrimination,  C.  E.  Sea¬ 

shore .  21 

III.  The  Determination  of  Mental  Imagery,  James  R.  Angell  61 


PREFACE 


It  has  often  been  felt  that  the  American  Psychological 
Association  ought  actively  to  undertake,  as  well  as  merely  to 
encourage,  systematic  contributions  to  research  and  the 
increase  of  scientific  knowledge.  In  response  to  this  sen¬ 
timent  the  Association  at  its  meeting  held  in  New  York  City, 
December  27,  28  and  29,  1906,  authorized  the  “creation  of 
a  permanent  committee  of  the  Association,  to  consist  of 
five  members,  which  shall  act  as  a  general  control  committee 
on  the  subject  of  measurements.  It  is  recommended  that  this 
committee  undertake  two  general  lines  of  work,  organizing 
as  many  subcommittees  as  it  shall  see  fit,  and  calling  to  its 
assistance  such  outside  help  as  it  may  desire:  first,  the  deter¬ 
mination  of  a  series  of  group  and  individual  tests,  with  refer¬ 
ence  to  practical  application,  and  second,  the  determination 
of  standard  experiments  of  a  more  technical  character.”^ 

The  present  report  is  the  work  of  the  committee  appointed 
in  execution  of  this  resolution.  The  subjects  assigned  for 
investigation  to  the  several  members  of  the  committee  will 
be  found  representative  of  the  two  main  lines  of  inquiry 
approved  by  the  Association.  They  are  as  follows:  C.  H. 
Judd,  tests  on  motor  activities;  W.  B.  Pillsbury,  determina¬ 
tion  of  intensity  of  sound;  C.  E.  Seashore,  discrimination  of 
pitch;  R.  S.  Woodworth,  difference  threshold  in  color  tone, 
and  free  and  controlled  association;  J.  R.  Angell,  determina¬ 
tion  of  mental  imagery. 

In  accordance  with  the  provisions  of  the  resolution  already 
partially  quoted,  the  committee  invited  Professors  R.  M. 
Yerkes  and  J.  B.  Watson  to  report  on  tests  for  color  vision 
in  animals.  Professor  Judd  invited  the  assistance  of  Professor 

1  A  somewhat  similar  committee  on  physical  and  mental  tests  was  appointed  by  the 
.\3s0ciati0n  in  189s,  and  reported  its  recommendations  at  the  annual  meeting  held  at 
Boston  and  Cambridge  in  1896. 


2 


PREFACE 


Raymond  Dodge  in  formulating  tests  on  eye  movement  in 
connection  with  the  study  of  nervous  fatigue  and  mental 
disease.  Professor  Woodworth  secured  the  cooperation  of 
Dr.  Lyman  Wells  in  his  work  on  association,  and  Professor 
Angell  has  been  assisted  in  his  work  by  Dr.  M.  R.  Fernald. 

The  publication  of  the  reports  has  been  delayed  much  be¬ 
yond  original  expectation  because  the  work  has  proved  un¬ 
expectedly  arduous  and  difficult.  Nevertheless,  the  com¬ 
mittee  has  made  explicit  reports  of  progress  at  each  of  the 
annual  meetings  of  the  association  since  its  appointment, 
and  Professor  Dodge’s  work  after  being  thus  reported  has 
already  appeared,  being  finally  published  in  conjunction  with 
Professor  Diefendorf.^ 

If  the  funds  appropriated  to  the  purpose  had  permitted,  the 
committee  would  probably  have  chosen  to  print  all  their 
material  under  one  cover.  This  was  not  practicable,  how¬ 
ever,  and  the  present  method  is  accordingly  accepted,  despite 
its  drawbacks.  The  reports  thus  far  arranged  for  are  to 
appear  as  follows:  In  the  present  volume — 

Methods  for  Determination  of  Intensity  of  Sound,  W.  B. 
Pillsbury. 

Measurement  of  Pitch  Discrimination,  C.  E.  Seashore. 

Determination  of  Mental  Imagery,  J.  R.  Angell. 

In  the  Animal  Behavior  Monographs,  Yerkes’  and  Wat¬ 
son’s  report  on  tests  of  the  color  vision  of  animals. 

In  the  monographs  of  the  Psychological  Review,  Wood¬ 
worth’s  and  Wells’  report  on  association  tests. 

Professor  Judd’s  work  on  motor  tests  has  been  unavoidably 
interrupted  and  it  is  not  possible  to  speak  with  certainty  of 
its  appearance. 

None  of  these  reports  is  to  be  considered  final.  Not  only 
are  there  outstanding  issues  to  be  further  studied,  but  after 
the  reports  have  been  subjected  to  criticism  and  practical  tests 
by  members  of  the  association  and  other  psychologists,  the 
committee  hopes,  if  continued  in  office,  to  print  a  more  author¬ 
itative  supplementary  report  in  which  the  final  judgment 

^  Experimental  Study  of  the  Ocular  Reactions  of  the  Insane  from  Photographic  Records, 
Brain,  1908,  Vol.  31,  pp.  451-492. 


PREFACE 


3 


of  ihe  committee  as  a  whole  will  be  registered  in  favor  of  one 
or  another  form  of  apparatus,  method  of  procedure,  etc. 
The  committee  will  welcome  all  specific  criticisms  and  sug¬ 
gestions. 


I 


METHODS  FOR  THE  DETERMINATION  OF  THE 
INTENSITY  OF  SOUND 

W.  B.  PiLLSBURY 

It  seems  to  be  the  function  of  a  report  of  this  kind  to  con¬ 
sider  the  general  principles  that  govern  the  problem,  to  com¬ 
pare  and  criticize  the  various  methods  that  have  been  used  and 
suggested,  and  to  offer  suggestions  based  on  tests  of  the 
different  methods  available. 

The  object  of  any  device  to  measure  the  sensitivity  of  the 
ear  must  be  to  produce  a  vibration  of  the  tympanic  membrane 
of  measurable  amplitude  or  intensity.  The  intensity  of  the 
sound  wave  at  the  ear  will  depend  upon  two  general  factors; 
the  intensity  of  the  sound  at  the  sounding  body  and  the  laws 
that  govern  the  distribution  of  the  sound  waves  about  that 
source.  To  know  how  intense  the  sound  will  be  at  the  ear 
one  must  know  how  great  the  amplitude  of  vibration  is  at 
the  sounding  body,  and  the  distance  from  the  ear  together  with 
the  way  in  which  the  sound  spreads  from  the  source,  or  one 
must  have  some  means  of  measuring  the  intensity  of  the  tone 
at  the  ear  itself.  A  complete  discussion  involves:  (i)  A 
study  of  the  different  methods  of  inducing  sounds  and  of 
measuring  the  intensity  of  the  sounds  that  are  produced. 
(2)  A  study  of  the  laws  that  control  the  distribution  of 
sound  waves  and  their  intensity  at  different  distances.  (3) 
Or  one  must  devise  some  methods  of  measuring  the  intensity 
of  the  tone  at  the  ear. 

Perhaps  the  method  of  inducing  a  sound  most  used  is  by 
falling  bodies,  either  freely  falling  or  by  the  pendulum. 
Practically  all  of  the  more  important  psychological  investi¬ 
gations  have  been  carried  on  by  that  method.  It  is  desirable 
therefore  to  determine  as  carefully  as  possible  the  controls 
that  are  necessary  in  this  method  and  the  means  of  measuring 


6 


W.  B.  PILLS  BURY. 


the  intensity  of  the  tone.  This  is  the  more  important,  as 
there  has  been  some  controversy  in  the  literature  over  the 
relation  between  the  height  of  fall  and  intensity.  Starke 
asserts  that  the  intensity  is  dependent  upon  the  product  of 
the  mass  and  the  height,  Vierordt  that  it  varies  as  mass 
times  the  height  raised  to  the  exponent  k  and  k  for  him  is 
0.6.  Tischer  came  to  the  opinion  that  k  varies  with  the  height 
and  with  the  mass  and  that  in  consequence  no  law  may  be 
asserted.  Fechner  also  expressed  the  opinion  that  k  was 
variable  and  must  be  determined  for  each  different  substance 
of  ball  and  plate. 

Obviously  the  first  problem  is  to  determine  the  relation  of 
the  intensity  to  the  height  of  fall.  I  attempted  this  in  three 
ways,  but  the  simplest  and  only  one  that  was  carried  through 
at  all  successfully  was  by  measuring  the  amplitude  of  vibration 
excited  in  a  fork  by  the  impact  of  a  rubber  ball  falling  from 
different  heights.  The  results  may  be  seen  in  the  curves 
that  are  published  herewith  (fig.  i).  In  general  it  will  be 
seen  that  the  amplitude  increases  much  more  rapidly  than 
the  square  root  of  the  height.  Each  set  was  taken  on  dif¬ 
ferent  days.  The  amplitude  was  measured  directly  with  a 
reading  microscope. 

To  show  the  relation,  the  square  roots  of  the  heights  have 
been  plotted  below  the  curve  plotted  from  the  amplitudes  of 
vibration  measured  directly  with  the  microscope.  Each  point 
is  the  average  of  from  fifteen  to  thirty  determinations.  The 
mean  variations  were  from  .2  to  .5  scale  divisions.  They  are 
stated  at  the  bottom  of  the  curve  for  each  point.  It  will  be  seen 
that  the  curve  of  amplitude  of  vibration  lies  between  the 
curve  of  the  square  roots  and  a  straight  line.  As  the  intensity 
of  the  sound  is  proportional  to  the  square  of  the  amplitude 
of  vibration  this  means  that  the  sound  increases  more  rapidly 
than  the  height  but  less  rapidly  than  the  square  of  the  height. 
It  should  be  added  of  course  that  this  result  will  not  neces¬ 
sarily  hold  for  any  other  ball  or  any  other  receiving  surface. 
If  the  work  in  the  determination  of  Weber’s  law  in  the 
Leipzig  laboratory  had  been  made  with  this  fork,  the  result 
would  be  quite  different  from  the  formulae  given  in  the 


DETERMINATION  OF  THE  INTENSITY  OF  SOUND. 


7 


literature.  What  the  actual  formula  for  their  apparatus  is 
no  one  can  know  now. 

In  order  more  nearly  to  approximate  the  conditions  of  use 
of  the  fall  phonometer,  I  attempted  to  measure  with  Wien’s 
resonator  one  component  of  the  noise  made  by  dropping 
balls  of  wood  and  hard  rubber  upon  different  surfaces.  The 
surfaces  chosen  were  not  particularly  suitable  to  give  perfect 
tones,  but  were  some  objects  about  the  laboratory  large 
enough  to  give  the  deep  tone  of  the  resonator,  120  VD.  One 
was  an  ordinary  wooden  box,  the  other  a  galvanized  iron  bas¬ 
ket.  They  were  always  placed  upon  a  spring  couch  padded 
with  cloth  to  prevent  transmission  of  the  tone  through  the 
floor  or  other  solid  objects.  Of  course  there  were  other  tones 
present  than  the  one  measured,  and  it  is  possible  that  the  differ¬ 
ent  components  were  favored  by  the  different  heights,  but 
uncertainty  in  the  quality  of  a  tone  is  nearly  as  grave  as  uncer¬ 
tainty  in  intensity.  The  results  are  given  in  figs.  2  and  3.  It 
will  be  seen  that  with  conditions  as  nearly  alike  as  they  could 
be  made  from  day  to  day  there  are  enormous  differences  both 
in  the  absolute  intensities  of  the  tone  and  in  the  character  of 
the  curve.  Some  show  practically  a  straight  line  or  an  in¬ 
crease  in  proportion  to  the  square  of  the  height,  others  are 
more  nearly  proportional  to  the  height.  These  statements 
both  rest  upon  the  assumption  that  the  intensity  of  the  tone 
is  proportional  to  the  square  of  the  rough  measurements  of 
the  deflections  seen  in  the  manometer  apparatus.  Each 
value  in  the  curve  is  the  average  of  five  readings  taken  in 
immediate  succession.  The  irregularity  of  the  different 
readings  is  probably  responsible  for  the  irregular  fluctuations 
in  certain  parts  of  the  curves.  It  may  be  argued  that  my 
materials  are  not  to  be  compared  with  the  ebony  or  ivory  or 
steel  plate  that  is  ordinarily  used  in  the  fall  phonometer. 
This  I  would  readily  grant,  but  would  insist  that  everything 
that  we  know  of  vibrating  plates  anywhere  indicates  that  the 
arrangement  of  nodes  depends  upon  the  point  of  the  plate  that 
is  struck  and  the  quality  of  the  tone  depends  upon  the  arrange¬ 
ment  of  the  nodes.  Then  too  there  is  nothing  in  the  character 
of  the  board  in  the  bottom  of  our  box  that  would  make  the 


8 


W.  B.  PILLS  BURY. 


tone  change  from  day  to  day,  that  is  not  also  found  in  the  plates 
ordinarily  used.  The  curve  of  sound  intensity  has  never 
been  worked  out  for  an  instrument  of  that  sort  and  until  it 
is,  one  can  know  nothing  of  the  sound  values  that  are  repre¬ 
sented  by  the  height  of  fall. 

The  explanation  of  the  disparities  is  to  be  conjectured  only, 
but  every  source  of  error  that  we  had  to  contend  with  is 
represented  in  the  actual  experiment  in  which  the  ear  re¬ 
places  the  resonator.  First  any  plate  vibrates  in  segments 
and  has  different  partial  vibrations.  Occasionally  variations 
in  a  single  result  were  undoubtedly  due  to  the  weakness  of 
the  component  that  we  were  measuring.  The  pitch  of  the 
complex  noise  would  be  noticeably  different  when  the  read¬ 
ing  was  found  to  be  unusually  low  or  high.  Anyone  who  has 
worked  with -the  ordinary  ebony  plate  fall  apparatus  will 
recall  that  frequently  a  tone  will  be  very  different  in  intensity 
and  quality  from  the  usual  ones.  The  well  known  fact  that 
the  same  intensity  induces  different  effects  at  different  pitches 
would  probably  suffice  to  account  for  the  different  appar¬ 
ent  intensities  of  these  tones.  In  addition  to  the  different 
conditions  of  reflection,  the  presence  of  different  bodies 
and  the  position  of  the  resonator  with  reference  to  the  walls 
undoubtedly  plays  a  very  important  part.  One  of  these  came 
to  our  notice  in  this  experiment.  It  had  grown  close  and  a 
door  was  opened  very  slightly.  The  opening  was  two  meters 
or  more  from  the  source  of  sound  and  about  the  same  distance 
away  from  the  line  between  the  source  and  the  resonator. 
Nevertheless  the  readings  at  once  dropped  very  markedly 
and  continued  lower  until  the  door  was  closed.  All  of  these 
irregularities  indicate  that  while  the  relation  of  intensity  to 
height  of  fall  is  fairly  close  in  the  tuning  fork,  that  for  the 
apparatus  that  is  ordinarily  used  the  variations  are  too  large 
and  irregular  to  enable  one  to  obtain  results  that  shall  be 
constant,  to  say  nothing  of  obtaining  absolute  measurements. 
Since  the  pendulum  implies  all  of  the  fundamental  principles 
of  the  freely  falling  balls,  in  addition  to  a  source  of  error  from 
the  tone  of  the  suspending  rod,  it  is  unquestionably  equally 
unreliable. 


DETERMINATION  OF  THE  INTENSITY  OF  SOUND. 


9 


Attempts  have  been  made  to  determine  the  absolute  limen 
by  the  use  of  falling  particles.  It  is  assumed  that  the  energy 
of  the  falling  body  may  all  be  transformed  into  sound  and  that 
the  product  of  the  height  and  the  mass  will  indicate  the  energy 
that  affects  the  ear  provided  suitable  corrections  are  made  for 
the  distance  from  the  ear.  Theoretically  this  is  open  to  two 
objections.  Certainly  not  all  of  the  energy  is  transformed  into 
sound.  Much  is  lost  in  heating  the  ball  and  the  plate.  How 
much  is  left  can  only  be  a  matter  of  conjecture.  Estimates 
of  the  energy  transformed  into  sound  under  other  conditions 
vary  from  i/iooo  for  the  telephone  to  1/15  that  Wead  esti¬ 
mated  for  this  tuning  forks.  Webster’s  more  recent  estimates 
for  a  more  economical  transformer  of  energy  than  the  ball  and 
falling  plate  would  place  the  loss  nearer  the  higher  figure. 
At  the  most  the  energy  computations  would  give  only  the 
maximum  values  and  whether  the  true  limen  were  i/io  or 
i/iooo  of  that  no  one  is  at  present  in  position  to  say.  In 
addition  to  this  disadvantage  of  not  knowing  what  the  results 
mean,  the  sound  produced  is  open  to  all  of  the  variations  that 
the  larger  ball  was  seen  to  show  in  the  experiment  just  de¬ 
scribed.  Early  in  this  investigation  an  attempt  was  made  to 
calibrate  a  Lehmann  acoumeter  by  determining  the  distance 
at  which  a  small  ball  of  cork  or  pith  might  be  heard  when  it 
fell  different  heights.  No  regular  results  could  be  obtained. 
First  the  different  reflections  at  different  positions  in  the  room 
made  it  impossible  to  draw  any  results  from  the  distance. 
The  sound  might  be  fully  as  intense  or  even  more  intense  at 
the  more  remote  as  at  the  nearer  distance.  The  same  height  of 
fall  often  gave  widely  different  results.  This  was  undoubtedly 
due  to  the  relation  of  the  position  of  impact  to  the  nodes  of 
the  plate.  Combined,  these  factors  made  the  method  abso¬ 
lutely  valueless.  The  theoretical  and  practical  disadvantages 
combined  make  the  falling  body  method  worthless  even  for 
student  exercises. 

A  second  method  is  the  tuning-fork  method  that  Wead  de¬ 
vised  and  which  in  a  modified  form  is  a  test  widely  used  by 
the  acoustician.  It  is  much  more  promising  theoretically 
since  it  offers  a  more  accurate  measure  of  the  absolute  inten- 


lO 


W.  B.  PILLS  BURY. 


sity  and  is  more  generally  applicable.  Wead’s^  method  was 
to  measure  the  amplitude  of  vibration  of  the  fork  and  to 
calculate  the  energy  of  the  vibration  from  the  dimensions 
of  the  fork  and  Young’smodulusforsteel.  He  tested  thedamp- 
ing  of  the  vibrations  and  the  weight  necessary  to  bend  the  fork 
and  found  that  the  formula  held  in  practice  with  surprising 
accuracy.  To  determine  the  potential  energy  in  the  Konig  Uta 
fork  the  following  formula  suffices.  The  potential  energy  in 
each  prong  equals  23.94  X  loa  Ergs.^  In  the  actual  experi¬ 
ments  a  (the  amplitude  of  vibration)  is  read  directly  by  a 
microscope  and  the  energy  is  computed  from  the  formula. 
The  experimenter  takes  the  reading  at  the  instant  the  sound 
disappears,  and  the  intensity  for  the  ear  is  computed  from  the 
energy  at  the  fork  and  the  distance  of  the  observer. 

Two  difficulties  may  be  pointed  out  in  connection  with  the 
method.  First  the  absolute  energy  transformed  into  sound 
waves  is  not  known,  and  cannot  be  accurately  separated  from 
the  energy  spent  in  heating  the  fork  and  in  communicating 
tremors  to  the  supports.  Wead  had  some  results  that  indi¬ 
cate  that  1/15  was  transformed  into  sound  but  did  not  regard 
the  results  as  conclusive.  The  second  source  of  error  iseven 
greater.  It  is  the  difficulty  in  determining  how  the  sound  will 
be  distributed.  Even  in  the  open  the  ground  will  reflect  or 
absorb  the  energy  differently,  and  in  a  closed  room  it  is  prac¬ 
tically  impossible  to  say  what  the  law  of  distribution  is. 
There  will  be  nodes  due  to  reflection  from  the  walls  and  other 
interferences  and  reinforcements  that  cannot  be  determined. 
In  the  open  the  wind  will  make  a  considerable  difference  in  the 
distribution.  In  spite  of  the  disadvantages  the  results  ob¬ 
tained  by  the  method  agree  fairly  well  with  those  obtained 
by  other  methods  as  will  be  seen  when  the  values  that  have 
been  determined  are  reported. 

The  general  formula  is 


^  Wead:  Am.  Journal  of  Science,  Se.  3,  Vol.  26,  p.  177. 


DETERMINATION  OF  THE  INTENSITY  OF  SOUND. 


II 


V  =  energy  of  fork;  b  =  width,  d  =  thickness,  I  =  length  of 
fork,  and  E  =  Young’s  modulus. 

For  psychologists  the  method  has  the  added  advantage  of 
using  instruments  that  are  everywhere  available.  Every 
laboratory  has  a  tuning-fork  and  a  microscope  and  that  is 
practically  all  that  is  necessary.  As  compared  with  the  fall 
phonometer  or  sound  pendulum  it  gives  a  tone  of  known  pitch 
and  of  constant  pitch.  The  variation  of  sensitivity  with  pitch 
makes  any  attempt  to  use  noise  uncertain.  Then  too  the 
constancy  of  pitch  will  obviate  the  uncontrollable  pitch  varia¬ 
tions  of  the  block  that  were  seen  to  make  the  free  falling  ball 
method  valueless.  Other  instruments  have  the  further  dis¬ 
advantage  that  one  cannot  change  the  intensity  at  will  except 
by  changing  the  distance  from  the  ear. 

The  ear  specialists  use  another  modification  of  the  tuning- 
fork  method  that  has  some  advantages.  Instead  of  measur¬ 
ing  the  amplitude  directly  they  measure  the  time  that  the 
fork  may  be  heard  by  a  defective  ear  and  compare  it  with 
the  time  that  the  same  tone  is  heard  by  a  normal  ear.  It 
has  been  determined  that  the  amplitude  of  vibration  of  the 
fork  at  two  times  will  be  proportional  to  in  which  e  is  the 
base  of  the  natural  logarithm,  t  is  the  time  during  which  the 
tone  is  heard  and  h  a  constant  that  depends  upon  the  rate  of 
damping  of  the  fork.  This  must  be  determined  for  each  fork. 
If  t  is  the  time  during  which  the  fork  is  heard  by  the  ear  to  be 
investigated,  and  4  the  time  it  will  be  heard  by  the  normal  ear, 
the  limen  H  is  expressed  by  the  equation  Hp  =  e 
It  might  be  objected  that  oneof  these  measurements  will  always 
be  subjective.  To  this  one  can  reply  that  the  variation  in  the 
normal  ear  is  probably  less  than  the  variation  in  the  objective 
conditions  under  the  most  favorable  circumstances.  If  the 
two  ears  be  placed  exactly  in  the  same  place  the  space  error 
of  the  distant  stimulus  will  be  avoided  which  should  fully 
compensate  for  any  change  in  the  sensitivity  of  the  standard 
ear.i  It  is  also  possible  to  determine  the  absolute  sensitivity 
of  the  normal  ear. 


1  Schaefer;  Nagel’s Physiologic,  Vol.  Ill,  pp.  4Q3-495. 


12 


W.  B.  PILLSBURY. 


One  of  the  most  convenient  instruments  for  determining  the 
limen  of  hearing  or  for  making  any  tests  that  require  absolute 
values  is  the  telephone.  The  telephone  may  be  easily  changed 
in  pitch  or  in  intensity  and  very  slight  gradations  of  the  tone 
may  be  obtained.  The  convenience  of  the  telephone  in  use 
rests  mainly  upon  the  fact  that  the  intensity  of  its  tone  varies 
directly  with  the  current  and  that  the  current  may  be  meas¬ 
ured  when  the  sound  itself  is  very  weak.  In  practice  it  is 
necessary  merely  to  establish  the  relation  between  a  given  cur¬ 
rent  and  some  measurable  intensity  of  the  tone  and  then  to 
measure  the  strength  of  the  current  when  the  tone  disap¬ 
pears.  The  strength  of  the  tone  at  the  limen  may  then  be 
calculated  directly.  The  direct  relation  between  strength  of 
current  and  intensity  of  tone  has  been  established  for  faint 
tones  by  Lord  Rayleigh  and  Wien. 

To  determine  the  energy  that  is  given  off  from  the  plate  of 
the  telephone  one  must  obviously  know  the  size  of  the  vibrat¬ 
ing  surface,  and  the  amplitude  of  vibration  of  each  part.  Wien^ 
expresses  the  energy  in  the  formula 


A 


C  p  o 
2k 


A2 


A  is  the  energy  that  passes  through  a  square  centimeter  of 
surface  in  a  second,  c  the  rate  of  transmission  of  sound,  p 
the  tone  of  the  plate,  k  the  index  of  specific  heat  and  A  the 
relative  pressure  amplitude.  A  may  be  expressed  in  the 
equation 


A 


0.147-- 


(2n  N)^ 

9 


where  n  is  the  time  of  excitation,  N  the  rate  of  the  tone,  R 
the  radius  of  the  vibrating  plate,  a  the  amplitude  of  vibration 
at  the  middle  of  the  plate  and  p  the  distance  between  the  ear 
and  the  plate.  In  practice  one  may  measure  the  amplitude 
of  vibration  of  the  plate  directly  by  attaching  a  fine  glass  rod 


^Max  Wien:  Ueber  die  Empfindlichkeit  des  Menschl.  Oohres  etc.  Pfliiger’s  Arch., 
vol.  97,  p.  I. 


DETERMINATION  OF  THE  INTENSITY  OF  SOUND. 


13 


to  the  center  of  the  plate  with  sealing  wax  and  measuring  the 
amplitude  with  a  microscope  with  micrometer  eye-piece. 
Measuring  the  current  offers  some  difficulties  if  one  uses  an 
alternating  current.  Wien  made  use  of  a  dynamometer  but 
I  have  found  it  more  satisfactory  to  use  either  the  Edelmann 
Saiten-galvanometer  or  to  use  Pierce’s  method  of  a  rectifier 
and  ordinary  galvanometer.  The  Edelmann  instrument  takes 
advantage  of  the  tendency  of  a  wire  carrying  a  current  to  move 
in  a  magnetic  field.  It  consists  of  a  fine  wire  mounted  in  the 
field  of  a  permanent  magnet.  The  movement  of  the  wire  may 
be  read  with  a  micrometer  eye-piece  or  in  certain  of  the  in¬ 
struments  may  be  photographed.  The  advantage  of  the  in¬ 
strument  is  that  the  moving  part  has  a  very  small  mass 
and  the  oscillations  induced  by  an  alternating  current  are  as 
easily  read  as  the  deviation  from  a  constant  current.  A  dis¬ 
advantage  emphasized  by  Pierce  is  that  the  own  tone  of  the 
wire  favors  one  rate  of  vibration  over  others. 

The  rectifiers  of  Pierce  depend  upon  the  fact  that  certain 
crystals  have  a  much  higher  resistance  in  one  direction  than 
in  another  to  small  currents.  I  had  such  a  rectifier  constructed 
of  molybdenite  and  found  that  an  ordinary  D’Arsonval 
galvanometer  was  as  sensitive  to  the  alternating  current  as  the 
smaller  Edelmann  instrument.  The  rectifier  is  much  cheaper 
and  easier  to  make  or  obtain  than  the  other  instrument,  and 
fully  as  convenient  to  use.  In  use,  then,  it  is  only  necessary  to 
determine  the  amplitude  of  vibration  of  the  telephone  for 
one  intensity  of  current  that  gives  an  amplitude  that  may 
be  conveniently  read,  and  that  may  also  be  easily  measured 
by  the  instrument  at  hand,  and  then  determine  the  current 
that  gives  a  liminal  tone.  The  liminal  amplitude  may  then 
be  computed  and  from  that,  the  energy  that  is  given  off  by 
the  telephone  and  the  amount  that  is  expended  upon  the  mem¬ 
brane  of  the  ear. 

We  have  also  to  consider  the  difficulty  in  determining  the 
part  of  the  tone  that  actually  falls  upon  the  ear,  which  gives 
as  much  trouble  here  as  elsewhere.  Wien  obviated  this 
by  closing  the  telephone  by  a  metal  cap  and  connecting  a  tube 
with  the  opening  that  might  be  inserted  in  the  ear.  It  ispossi- 


14 


W.  B.  PILLSBURY. 


ble  to  assume  that  all  of  the  energy  affects  the  ear  under  these 
circumstances.  The  error  in  this  assumption  is.  probably 
less  than  on  any  assumption  that  one  can  make  of  the  dis¬ 
tribution  of  sound  where  the  source  and  the  ear  are  at  a  dis¬ 
tance  from  each  other. 

One  other  difficulty  that  the  telephone  presents  is  that  the 
breaking  of  the  circuit  is  always  followed  by  a  marked  click  that 
is  more  noticeable  than  the  continuous  tone.  The  intensity 
of  the  click  depends  upon  two  factors.  First  the  regular 
vibrations  do  not  ordinarily  release  the  plate  altogether. 
Residual  magnetism  holds  the  diaphragm  nearer  the  pole  of 
the  magnet  than  its  position  of  rest  during  the  entire  period 
of  its  vibration.  This  may  be  observed  through  the  microscope. 
Then,  too,  the  forced  vibration  due  to  the  current  probably 
does  not  cause  so  great  a  vibration  amplitude  as  the  natural 
vibration  of  the  plate  that  appears  when  the  current  is  cut  off. 
More  important  than  either,  however,  is  the  fact  that  the 
natural  pitch  of  the  plate  (usually  about  900  vd.)  corresponds 
to  a  rate  of  vibration  to  which  the  ear  is  more  sensitive  than 
the  lower  pitches  ordinarily  used  in  the  laboratory  experi¬ 
ments.  Whatever  the  cause,  the  disturbance  due  to  the  click 
is  very  marked.  Dr.  Shepard,  working  in  my  laboratory,  found 
that  the  click  could  be  lessened  to  the  point  of  not  being 
noticed  if  two  tones  were  superimposed  upon  the  telephone. 
He  used  the  commercial  current  of  60  cycles  and  a  250  VD 
fork.  The  physical  basis  for  the  effect  is  obscure,  but  the 
empirical  effect  is  obvious. 

Taken  all  in  all  the  telephone  is  probably  the  most  satis¬ 
factory  instrument  to  use  for  sound  experiments  in  the  psy¬ 
chological  laboratory.  It  can  be  made  to  give  a  constant 
sound  that  can  be  varied  at  will  in  pitch,  in  intensity  and 
duration.  It  can  be  applied  to  the  measurements  of  inten¬ 
sity  in  all  fields,  is  invaluable  in  experiments  in  rhythm  when 
combined  with  an  interrupting  apparatus  and  has  a  number  of 
uses  in  subsidiary  experiments.  In  addition,  the  apparatus 
required  is  less  expensive  than  many  of  the  pieces  sold  as 
instruments  for  the  measurement  of  audition  and  the  parts 
can  be  used  in  many  other  ways.  One  needs  the  telephone 


DETERMINATION  OF  THE  INTENSITY  OF  SOUND. 


15 


itself,  a  galvanometer,  a  rectifier  if  one  uses  an  alternating 
current,  a  tuning  fork,  otherwise,  resistances  that  may  be 
adjusted  and  a  microscope  for  measuring  the  vibration  of  the 
plate.  An  induction  coil  that  may  be  used  as  a  step-down 
transformer  is  also  convenient  in  saving  resistance.  All  of 
these  pieces  are  needed  for  other  experiments  and  the  cost  of 
those  that  are  not  likely  to  be  on  hand  will  be  less  than  fifty 
dollars.^ 

In  addition  to  these  instruments  that  have  been  tested  one 
might  mention  the  instruments  that  have  been  used  by  Lord 
Rayleigh,  by  Webster,  and  by  Toepler  and  Boltzman.  Lord 
Rayleigh^  used  cans  of  ferrotype  or  tin  made  to  vibrate  by 
an  electro-magnet.  They  were  used  to  measure  the  rela¬ 
tive  sensitiveness  of  the  ear  to  different  tones  and  no  attempt 
was  made  to  determine  the  absolute  intensity.  The  cans  for 
different  pitches  were  made  similar  in  all  of  their  parts.  In¬ 
tensity  of  the  tones  was  determined  by  measuring  the  ampli¬ 
tude  of  vibration  of  the  rims  by  a  microscope.  The  magnets 
were  within  the  cans  and  supported  from  the  bottom.  The 
alternating  electric  impulses  were  communicated  by  electric 
tuning  forks.  As  the  use  of  the  instrument  was  restricted  to 
measuring  relative  intensities  extended  description  need  not 
be  given  in  this  connection. 

V ery  similar  in  principle  is  Webster’s^  instrument.  In  brief 
it  consisted  of  a  resonator  made  to  speak  by  vibrations  of 
a  plate  of  ferrotype  that  in  turn  was  made  to  vibrate  by  an 
electric  tuning  fork.  The  ferrotype  plate  closes  one  end  of 
the  resonator  and  is  connected  with  the  tuning  fork  by  a 
metal  rod.  The  amplitude  of  vibration  of  the  diaphragm  may 

^  Seashore’s  Audiometer  may  be  mentioned  as  an  instrument  that  makes  use  of  the 
telephone.  For  Wien’s  method  it  would  need  some  means  of  measuring  the  vibra¬ 
tion  of  the  telephone  plate  and  would  also  be  more  convenient  if  the  resistance  could 
be  changed  by  smaller  gradations.  It  would  also  need  a  tuning  fork  or  some  method 
of  interrupting  a  current  to  give  a  pure  tone.  In  many  respects  it  is  more  convenient 
to  use  an  ordinary  resistance  box  and  telephone  with  the  forks  and  other  auxiliary 
apparatus  that  are  at  hand  in  the  laboratory. 

^  Lord  Rayleigh :  On  the  Relation  of  the  Sensitiveness  of  the  Ear  to  Pitch,  Investi¬ 
gated  by  a  New  Method.  Phil.  Mag.,  14,  1907,  p.  596. 

*  .\.  G.  Webster:  On  the  Mechanical  Efficiency  of  the  Production  of  Sound.  Boltz¬ 
mann  Festscrichrifl,  1904,  p.  866. 


i6 


W.  B.  PILLS  BURY. 


be  read  directly  by  a  microscope.  The  instrument  was  used 
by  Webster  to  measure  the  energy  used  and  transmitted  by 
sounding  bodies,  but  would  serve  admirably  as  a  reliable 
source  of  sound. 

Toepler  and  Boltzmann  measured  the  concentration  of  the 
sound  in  a  closed  tube  by  an  interference  method.  It  is  more 
complicated  than  the  methods  described  and  need  not  be 
considered  here. 

In  concluding  this  series  of  methods  it  may  be  interesting 
to  compare  the  results  so  far  obtained.  The  most  striking 
result,  as  well  as  the  one  that  shows  most  difference  in  the 
values,  is  the  difference  in  sensitiveness  to  sounds  of  differ¬ 
ent  pitches.  The  results  of  Toepler  and  Boltzmann,^  Wead, 
Wien,  Lord  Rayleigh  and  Zwaardemaaker  and  Quix  are 
given  in  parallel  columns.  The  first  column  gives  the  rate 
of  the  tone  in  question  and  the  column  under  the  name 


N. 

T.  AND  B. 

Wd. 

Wn. 

R. 

Z.  AND  Q. 

32 

i 

1 

550 

5° 

4. 10-6 

64 

37 

96 

2,8.  lo-i 

100 

7.10-® 

128 

2,7.10-1 

181 

3 • 

192 

4,6  .  lO-l 

200 

3. 1 0-11 

256 

83.10-6 

8.5.10-9 

5,5-10-^ 

384 

28.10-'^ 

6 . 10-9 

3,4  10-9 

400 

3  ■  10-^^ 

512 

1,97.10-6 

768 

31 . 10-^ 

2,5.10-1 

800 

7.10-'' 

1024 

II . 10-^ 

2,7 . 10-1 

1536 

22 . 10-6 

1600 

I  .  10-16 

2048 

71 . 10-^ 

3200 

S  •  10-^® 

6400 

3.10-^ 

12800 

S  •  lo-i^ 

*  Toepler  and  Botzmann :  Pog.  Ann.,  141, 1870,  p.  317. 


DETERMINATION  OF  THE  INTENSITY  OF  SOUND. 


17 


the  energy  in  ergs  necessary  to  excite  the  ear.i  It  should  be 
added  that  Zwaardemaaker  and  Quix  used  tuning  forks  in 
their  determinations,  and  the  values  I  have  given  are  the 
results  as  corrected  for  certain  errors  by  Wien  in  the  second 
appendix  to  his  article  cited  above. 

The  most  striking  feature  of  all  of  these  experiments  is  the 
variation  in  the  results.  This  variation,  it  will  be  noticed, 
is  not  only  in  the  absolute  values  but  also  in  the  relative  sensi¬ 
tivity  to  different  pitches.  The  values  do  not  seem  to  depend 
upon  the  method  alone.  It  should  be  noted,  too,  that  after 
Wien  published  his  results  that  showed  surprising  differences 
in  the  limen  for  different  pitches.  Lord  Rayleigh  repeated  his 
tests  with  the  bells  above  mentioned  and  got  results  that 
showed  that  the  limina  for  tones  from  512  to  85  are  related 
as  follows,  expressed  with  the  limen  for  512  as  unity:  512,  i ; 
256,  1.6;  128,  3.2;  85,  6.4.  He  adds  that  he  can  see  no  reason 
for  the  disparity  between  his  results  and  Wien’s.  Very  ob¬ 
viously  the  results  need  to  be  gone  over,  but  it  seems  to  be  no 
part  of  a  report  such  as  this  to  undertake  the  work.  A  new 
determination  would  have  only  the  value  that  the  methods 
and  reputation  of  the  worker  give  it  and  the  older  workers 
have  apparently  left  nothing  to  be  desired  either  in  care  or  in 
the  distinction  of  the  men  themselves. 

Another  method  of  varying  the  intensity  of  sound  has  been 
suggested  and  an  instrument  embodying  it  has  been  put  upon 
the  market.  I  refer  to  the  audiometer  of  McCallie.  I  had 
hoped  to  have  an  opportunity  of  testing  the  instrument, 
but  up  to  this  time  none  has  presented  itself.  In  essentials  it 
consists  of  some  source  of  sound  in  a  box  and  the  intensity 
is  varied  by  changing  the  size  of  the  apperture  that  emits  the 
sound.  A  priori  the  main  objection  to  the  plan  is  the  fact  that 
the  intensity  of  sound  will  not  vary  directly  with  the  area  of 
the  opening.  Lord  Rayleigh  has  shown  that  the  sound  will 
be  very  little  affected  by  changing  the  width  of  the  slit  as 
compared  with  the  length,  where  the  slit  is  narrow.  A  change 

^The  values  in  the  columns  Wn.  and  Z.  and  Q.  assume  that  below  3500  VD  two 
vibrations  suffice  to  excite  a  tone,  that  seven  are  needed  at  6400  and  twenty  at  12800, 
while  in  the  others  the  figures  indicate  work  done  on  the  ear  in  a  second. 


i8 


W.  B.  PILLS  BURY. 


in  length  from  .5  inch  to  .28  inch  compensated  a  change  in  the 
width  of  the  slit  from  .004  to  .020  inch.  This  proportion  would 
certainly  not  hold  for  wider  slits  but  the  law  for  the  relation 
between  the  area  of  opening  and  intensity  of  tone  is  not  known 
and  would  probably  be  fairly  complicated.  The  instrument 
also  uses  a  noise  rather  than  a  pure  tone,  which  in  view  of  the 
results  given  above  renders  the  measurement  uncertain.^  Rub¬ 
ber  tubes  are  used  to  carry  the  tone  to  the  ear  as  in  the  pho¬ 
nograph.  This  has  the  advantage  of  removing  any  uncer¬ 
tainty  of  the  nature  of  the  reflection  from  walls  and  the  dis¬ 
tribution  of  sound  that  constitutes  an  important  source  of 
error  in  the  experiments  that  make  use  of  free  distribution 
through  the  air. 

Of  the  sources  of  sound  discussed  here  the  telephone  is  the 
most  convenient,  and  probably  the  results  are  as  accurate  as 
any.  Next  comes  the  damping  method  applied  to  the  tuning 
fork,  the  others  in  a  third  group.  It  should  be  remarked  that 
all  of  the  methods  make  certain  assumptions  in  the  calcula¬ 
tion  of  absolute  values  that  may  be  in  error  and  if  in  error, 
would  serve  to  account  for  some  at  least  of  the  divergence 
in  results.  Obviously  a  highly  desirable  advance  in  acous¬ 
tics  is  the  removal  of  these  sources  of  error  and  the  develop¬ 
ment  of  methods  more  suited  to  direct  measurements. 

Aside  from  this  group  of  methods  that  depend  upon  the 
measurement  of  the  sound  emitted  from  the  source,  others 
are  or  should  some  day  become  possible  that  depend  upon  the 
measurement  of  the  sound  at  the  ear.  The  factors  that  make 
for  errors  in  the  calculation  of  the  sound  that  passes  through 
any  given  area  at  a  distance  from  the  source,  even  if  the  in¬ 
tensity  of  the  sound  at  the  source  is  accurately  known,  are 
many;  some  of  them  have  been  indicated  above.  The  deflec¬ 
tions  and  reflections  induced  by  walls  and  obstructions  are 
obvious.  To  these  one  must  add  the  interference  between  the 
original  and  the  reflected  wave  that  tends  to  produce  a  dead 
region  at  a  little  distance  from  the  wall.  To  these  uncertain¬ 
ties  of  reflection  one  must  add  the  fact  demonstrated  by  Web- 

1  Professor  Angell  tells  me  that  the  sound  has  a  tonal  quality  although  it  is  described 
in  the  catalogue  as  a  noise. 


DETERMINATION  OF  THE  INTENSITY  OF  SOUND. 


19 


ster  that  the  nature  of  the  surface  has  a  marked  effect  on  the 
character  of  the  transmission.  He  found  that  a  sound  could 
be  heard  three  times  as  far  over  water  as  over  a  lawn.  He 
argues  that  the  grass  acts  as  a  black  body  in  absorbing  sound. 
The  probability  that  other  surfaces  may  show  similar  differ¬ 
ences  and  the  complete  absence  of  knowledge  on  the  point 
may  well  serve  to  enforce  caution  in  calculating  the  amount 
of  energy  that  passes  through  any  area  at  a  distance  from  the 
sounding  body.  One  must  look  with  a  measure  of  skepticism 
upon  all  methods  that  have  made  such  calculations  and  these 
include  practically  all  the  results  of  the  men  whose  work  has 
been  cited  above.  Wien’s  results  alone  are  derived  with  the 
ear  placed  so  as  to  receive  the  entire  energy  of  vibrations, 
and  even  his  receptacle  may  permit  certain  losses. 

These  considerations  make  desirable  some  means  of  measur¬ 
ing  the  sound  wave  that  actually  falls  upon  the  ear.  This 
might  be  accomplished  were  it  possible  to  obtain  an  instrument 
delicate  enough  to  measure  the  force  exerted  or  the  work  done 
by  the  vibrations.  Two  instruments  approach  this  degree  of 
sensibility,  the  telephone  of  Pierce^  and  the  receiving  instru¬ 
ment  of  Webster.  The  Pierce  instrument  measures  the  elec¬ 
tric  current  induced  in  the  telephone  circuit  by  the  displace¬ 
ment  of  the  plate  of  the  telephone  by  the  sound  wave.  The 
apparatus  for  measuring  the  current  was  described  above. 
This  with  Pierce’s  adjustment  was  barely  adequate,  but  it  is 
no  doubt  possible  with  practice  to  get  a  more  sensitive  adjust¬ 
ment.  Webster’s  instrument  has  not  been  described  in  print, 
and  I  have  never  seen  it,  but  I  am  told  that  in  essentials  it  con¬ 
sists  of  a  glass  plate  that  is  made  to  vibrate  by  the  sound  wave 
and  the  slight  movements  of  the  plate  are  measured  by  an  inter¬ 
ference  method.  How  delicate  it  may  be  I  do  not  know.  It  is 
highly  desirable  that  one  or  the  other  of  these  methods  should 
be  perfected  to  the  point  that  will  permit  them  to  check  the  re¬ 
sults  obtained  by  other  methods.  Even  if  one  could  measure 
the  energy  where  the  ear  is  to  be,  when  the  ear  replaces  the 
measuring  instrument  the  conditions  would  be  changed  in  some 

1  G.  W.  Pierce:  A  Simple  Method  of  Measuring  the  Intensity  of  Sound.  Proc. 
Am.  Acad.,  vol.  43,  p.  377. 


20 


W.  B.  PILLSBURY. 


small  degree,  the  head  and  body  would  reflect  sound  differ¬ 
ently  from  the  plate  or  telephone.  This  error  would  undoubt¬ 
edly  be  much  less  than  those  that  are  made  in  assuming  a 
law  for  the  distribution  of  sound  in  an  open  space,  but  still 
would  hardly  be  negligible.  The  method  when  developed 
will  probably  be  more  accurate  than  any  that  depends  upon 
the  energy  developed  by  a  source  of  sound,  and  if  the  promise 
is  not  altogether  realized  it  will  at  least  provide  an  invaluable 
check  upon  the  other  methods. 

RECOMMENDATIONS. 

We  may  close  with  a  series  of  specific  suggestions  based 
upon  the  tests  and  the  examination  of  the  literature. 

1.  One  should  always  use  a  tone  as  pure  as  possible  as  the 
stimulus.  A  noise  is  nothing  other  than  a  tone  of  unknown 
pitch  or  a  complex  of  tones  of  unknown  pitch.  So  much  of 
the  sensitiveness  of  the  ear  depends  upon  the  pitch  that  if 
that  be  unknown  or  neglected  the  result  is  uncertain.  The 
preference  of  most  psychologists  for  the  use  of  noise  seems 
entirely  without  rational  support. 

2.  All  methods  that  depend  upon  the  impact  of  falling 
bodies  give  uncertain  results,  (a)  The  sound  is  always  a 
noise,  (b)  The  pitch  of  the  noise  can  not  be  kept  constant, 
(c)  No  known  relation  exists  between  the  energy  developed 
and  the  amount  transformed  into  noise.  While  the  relative 
intensities  vary  with  the  height  of  fall,  the  method  gives  no 
means  of  obtaining  absolute  measurements. 

3.  The  most  accurate  and  convenient  instrument  for 
absolute  measurements  is  a  telephone  actuated  by  a  tuning 
fork  or  alternating  current.  Some  method  of  measuring  the 
strength  of  current  and  a  micrometer  for  measuring  the  am¬ 
plitude  of  vibration  of  the  plate  is  also  required. 

4.  Slightly  less  expensive  and  simpler  is  the  equipment  for 
using  the  tuning-fork  method.  A  fork  with  stable  mounting, 
and  a  micrometer,  or  a  fork  whose  rate  of  damping  has  been 
determined  is  all  that  is  requird.  The  results  are  probably 
less  accurate  than  those  obtained  by  the  telephone,  but  that 
is  not  altogether  assured. 


THE  MEASUREMENT  OF  PITCH  DISCRIMINATION: 
A  PRELIMINARY  REPORT. 


By  C.  E.  Seashore. 

This  report  was  called  for  by  the  Association  in  the  belief 
that  the  systematic  criticism  and  trial  of  current  methods 
and  means,  and  the  statement  of  the  essential  implications, 
would  economize  effort  for  future  workers  and  further  the 
prospects  of  practical  applications  of  the  test.  The  measure¬ 
ment  may  be  made  by  so  many  different  kinds  of  apparatus  of 
various  degrees  of  worth,  by  so  many  methods  of  procedure 
more  or  less  adequate,  under  so  many  hypotheses  more  or 
less  specious,  for  so  many  purposes  more  or  less  legitimate, 
that  the  situation  is  very  complicated. 

This  preliminary  report  is  limited  to  a  bare  outline  of  the 
nature  of  the  problem  with  tentative,  positive  recommenda¬ 
tions  in  regard  to  the  procedure. 

The  outline  features  here  presented  have  served  and  should 
continue  to  serve  as  an  aid  in  concentrating  research  on  the 
most  essential  problems.  Among  the  problems  already  taken 
up  in  the  Iowa  Laboratory  are  the  following:  the  physical 
constants  and  variables  in  the  tuning  fork,  the  string,  the 
reed,  the  pipe,  the  tone  variator  (bottle),  and  the  siren; 
the  adaptation  of  different  types  of  instruments  to  different 
needs,  and  different  psychophysic  methods;  the  evaluation  of 
one  method  in  terms  of  another,  e.g.,  the  method  of  the  “aver¬ 
age  of  the  middle  third’’  in  terms  of  the  method  of  right  and 
wrong  cases;  the  validity,  i.e.,  the  degree  of  certainty  or 
constancy  in  the  measurement;  the  effect  of  intensity,  dura¬ 
tion,  length  of  interval,  order  of  trial,  tone  quality  (timbre) 
and  prolonged  trial  (fatigue),  on  the  discrimination ;  the 
relation  of  consciousness  of  difference  to  actual  difference 
(very  surprising);  the  lower  limit  of  tonality;  the  relative 


22 


C.  E.  SEASHORE. 


discriminative  sensibility  for  pitch  within  the  tonal  range; 
the  relations  of  pitch  discrimination  to  other  musical  capaci¬ 
ties,  e.g.,  the  sense  of  rhythm,  ability  in  singing  and  playing, 
the  perception  of  dissonance  and  the  appreciation  of  music; 
also  its  relation  to  musical  education  and  musical  environ¬ 
ment;  the  possibility  of  improving  the  capacity  with  practice; 
the  establishment  of  norms;  the  relation  of  the  cognitive  to 
the  physiological  threshold;  variation  with  age,  sex,  and  gen¬ 
eral  intelligence  and  special  intelligence;  and  pedagogical  appli¬ 
cations.  This  report  is  based  essentially  upon  the  result 
obtained  up  to  date  in  the  investigations  just  named;  general 
acknowledgment  to  these  workers  is  here  given.  Volume  VI 
of  the  University  of  Iowa  Studies  in  Psychology  will  be  devoted 
to  the  publication  of  some  of  these  investigations. 

These  are  large  problems.  A  few  have  been  solved  in  part, 
but  most  of  them  require  a  long  time.  This  announcement 
of  problems  should  in  no  sense  be  regarded  as  preempting  the 
field.  What  we  need  is  elimination  of  useless  effort,  coopera¬ 
tion,  and  stimulation  of  interest  on  the  part  of  capable  inves¬ 
tigators.  The  committee  therefore  most  cordially  urges  those 
who  are  engaged  in,  or  can  undertake,  research  in  this  direc¬ 
tion  to  correspond  with  the  chairman  of  this  sub-committee 
in  order  that  the  work  may  be  correlated.  There  will  be  no 
restrictions  or  interference,  but  it  may  enable  us  to  avoid 
known  snags  and  duplication  of  effort,  and  should  ensure 
effective  collaboration. 

The  sub-committee  presents  this  preliminary  report  as  an 
aid  to  the  better  formulation  of  work  in  the  subject.  The  ex¬ 
tended  reports  of  research  on  these  problems  will  be  published 
whenever  and  wherever  convenient,  and  it  is  to  be  hoped 
that,  after  a  few  years,  the  results  may  be  summarized  into 
a  more  comprehensive  and  authoritative  report — a  sequel 
and,  in  part,  a  result  of  this  preliminary  report. 

There  are  many  and  varied  demands  for  the  measurement 
of  pitch  discrimination:  e.g.,  in  the  decision  about  whether 
or  not  to  start  a  child  in  a  technical  musical  education ;  in  the 
classification  of  pupils  for  the  purpose  of  class  instruction; 
in  anthropological  measurements;  in  psychological  measure- 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


23 


ment  as  a  means  of  determining  the  specific  laws  of  pitch 
hearing  and  production,  as  well  as  in  the  working  out  of  the 
general  laws  of  mental  life  such  as  in  attention,  fatigue, 
association,  suggestion,  imagery,  memory,  automatism,  and 
affective  tone ;  and  in  the  countless  applications  of  these  psy¬ 
chological  and  psychophysical  facts  to  a  theory  of  esthetics, 
with  reference  to  the  application  and  the  expression  of  music 
as  well  as  to  the  pedagogy  of  musical  instruction. 

I.  General  Account  of  Apparatus. 

Pitch  discrimination  is  usually  measured  by  determining 
the  least  perceptible  difference  in  the  pitch  of  two  successive 
tones.  Without  actual  measurement,  the  pitch  discrimination 
is  often  estimated  quite  accurately,  e.g.,  by  observing  the 
accuracy  in  singing  and  in  the  tuning  and  playing  of  certain 
instruments,  as  well  as  in  the  ability  to  analyze  musical  clangs. 
The  measurement  may  be  made  by  means  of  tuning  forks, 
stringed  instruments,  reeds,  pipes,  sirens,  etc.  The  relative 
merits  of  these  instruments  and  the  means  for  using  them 
should  be  set  forth  in  a  later  report. 

The  measurement  of  pitch  discrimination  has  a  short  his¬ 
tory.  While  musicians  have  always  wrestled  with  the  prob¬ 
lem  in  a  general  way,  the  significance  of  accurate  measure¬ 
ment  has  not  been  comprehended  until  in  recent  years.  It 
may  truly  be  said  that  the  discovery  of  the  real  significance 
of  the  measurement  of  pitch  discrimination  came  gradually 
with  the  discovery  of  the  sources  of  error  which  enter  into  the 
test  as  worked  out  in  the  psychological  laboratories. 

Much  time  and  energy  have  been  wasted  and  false  returns 
have  been  announced  from  experiments  with  unreliable  appa¬ 
ratus.  Instruments  for  one  kind  of  work  have  been  used  for 
another.  There  has  been  no  satisfactory  cooperation  in 
the  designing  of  instruments  and  in  the  securing  of  critical 
tests  before  putting  the  apparatus  on  the  market.  The  makers 
have  not  had  the  right  encouragement  or  discouragement. 


24 


C.  E.  SEASHORE. 


A.  Factors  in  Apparatus. 

The  principal  variables,  the  control  of  which  determines 
the  reliability  of  the  apparatus,  are:  (i)  form  of  the  vibrating 
body — fork,  reed,  string,  etc.,  (a)  with  reference  to  the  selec¬ 
tion  from  these  fundamental  types  of  vibrating  bodies,  and 
{h)  with  reference  to  the  favorable  construction  of  each  within 
its  own  style;  (2)  the  quality  of  material  and  workmanship; 
(3)  accuracy  of  tuning;  (4)  mode  of  energizing;  (5)  mode  of 
reinforcement  and  purifying;  and  (6)  constancy  of  condi¬ 
tions.  With  these  requirements  in  view,  one  must  take  into 
consideration,  among  other  factors,  the  following. 

1.  Reliability.  The  measurement  is  made  in  terms  of 
double,  or  complete,  vibrations  (vd.)^  As  a  most  serviceable 
standard  of  reliability  in  the  apparatus  and  accuracy  in  tun¬ 
ing,  we  recommend  =^.05  vd.  for  increments  from  .5  to  2  vd.; 
±  .  I  vd.  for  increments  from  3  to  5  X^d.;  and  ±.2  vd.  for  in¬ 
crements  larger  than  5  vd.  This  concerns  the  reliability  of 
the  original  tuning,  or  the  ability  to  set  or  tune,  as  well  as  the 
reliability  of  the  apparatus,  i.e.,  freedom  from  progressive 
or  constant  errors. 

We  must  distinguish  between  rough  and  accurate  tests. 
One  is  as  legitimate  as  the  other  in  its  place.  We  must  also 
distinguish  in  the  latter  between  tests  of  persons  who  have  a 
high  threshold  and  those  who  have  a  very  fine,  low  threshold. 
This  discussion  of  apparatus  is  concerned  with  accurate  tests 
in  which  small  sources  of  error  would  be  disturbing. 

2.  Availability.  In  addition  to  beingreliable,  the  apparatus 
must  also  prove  available,  e.g.,  obtainable  as  regards  cost, 
adapted  to  the  necessary  method  which  serves  a  specific  pur¬ 
pose,  and  adequate  to  the  present  needs  as  regards  time  saving  , 
accuracy,  etc. 

The  various  types  of  tuning  forks,  strings,  reeds,  bottles, 

1  Much  confusion  in  terminology  and  in  the  interpretation  of  records  has  resulted 
from  the  fact  that  in  some  scientific  work,  notably  the  French,  the  single  vibration 
(vs.)  has  been  used  as  a  unit,  and  both  single  and  double  are  spoken  of  as  vibrations, 
ft  is  therefore  desirable  to  use  the  differentiating  abbreviation  vd.  in  this  country  where 
the  double  vibration  is  the  unit. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


25 


and  sirens,  each  have  some  legitimate  place.  Thus  the 
tone  variator  is  our  only  available  instrument  for  the  measure¬ 
ment  of  gradual  change  in  pitch;  a  well  built  monochord  is 
very  convenient  for  rough  tests  in  a  class ;  and  a  pair  of  electric¬ 
ally  energized  tuning  forks  with  selective  resonators  is  very 
satisfactory  for  the  testing  of  an  individual  or  group  of  individ¬ 
uals  whose  thresholds  are  known  to  correspond  to  the  tun¬ 
ing  of  the  forks,  and  when  a  sufficient  number  of  trials  can 
be  made  to  justify  the  use  of  the  method  of  right  and  wrong 
cases.  But  the  first  two  of  these  are  not  reliable  for  accurate 
work  and  the  last  is  not  available  for  the  tests  most  used. 

We  therefore  recommend  that,  before  the  records  are  made, 
the  adaptation  of  the  instrument  to  the  measurement  in 
question  be  carefully  considered. 

3.  The  Tonal  Register.  In  many  cases  it  is  necessary  to 
make  measurements  at  different  levels,  of  pitch.  This  ma}^ 
fix  for  us  in  part  the  choice  of  apparatus.  Some  instruments 
are  adapted  for  very  limited  range  and  others  for  an  extensive 
range  of  pitch.  In  statistical  and  other  comparative  tests, 
it  is  desirable  that  we  should  accumulate  data  with  reference 
to  some  standard  pitch  that  is  decidedly  favorable  and  can 
command  general  adoption. 

In  view  of  the  available  apparatus,  the  agreeableness  of 
the  tone,  the  fact  that  it  represents  the  middle  of  the  regis¬ 
ter  of  tones  most  used,  that  it  is  in  relatively  the  most  sensi¬ 
tive  register,  and  that  it  is  the  international  standard  of  pitch, 
we  recommend  that  standard  tests  be  taken  at  a',  435  vd. 

For  the  sake  of  securing  uniformity,  although  the  matter 
is  quite  arbitrary,  we  also  recommend  that  the  series  of  in¬ 
crements  upon  that  standard  be  chosen  above  rather  than 
below  standard. 

4.  Increments.  In  a  discrimination  test  of  this  sort,  the 
change  of  pitch  must  of  course  be  an  absolute  step,  not  a 
gradual  change.  The  range  of  increase  should  be  so  chosen 
as  to  cover  all  cases  in  normal  groups.  .5  vd.  for  the  smallest 
increment  and  30  vd.  for  the  largest  increment  at  the  stand¬ 
ard  of  435  vd.  is  adequate  for  most  purposes. 

Within  this  range  the  arbitrary  steps  chosen  in  extensive 


26 


C.  E.  SEASHORE. 


experiment  seems  to  require,  (i)  as  small  difference  as  would 
have  any  significance  for  a  group  test  in  consideration  of 
economy  and  trustworthiness,  and  (2)  intervals  of  relatively 
equal  psychophysical  significance. 

The  increments  should  be  chosen  in  some  geometrical  ratio, 
but  the  strict  geometrical  ratio  would  necessitate  superfluous 
steps — too  small  increments  at  either  end  of  the  series.  Fur¬ 
thermore, there  is  a  real  advantage  in  maintaining  the  incre¬ 
ments  in  whole  units  without  using  fractions  of  a  vibration. 
We  therefore  recommend  as  economical  and  serviceable,  the 
following  series  of  increments  above  the  standard  a^  435  vd.: 
.5,  I,  2,  3,  5,  8,  12,  17,  23,  and  30  vd.  It  will  be  observed 
that,  except  for  the  first  two  steps,  this  is  an  arithmetical 
progression  of  the  second  order. 

It  is  probably  just  as  valuable  for  us  to  know  whether  the 
threshold  is  .5  vd.  or  i  vd.  for  the  fine  ear  as  it  is  to  know 
whether  it  is  5  vd.  or  8  vd.  for  a  medium  ear,  or  23  vd.  or  30 
vd.  for  a  very  inferior  ear.  This  equality  is  of  course  only 
an  empirical  approximation,  for  convenience  and  economy. 

5.  Sounding.  In  view  of  the  fact  that  timbre,  intensity, 
duration,  direction  of  sources,  etc.,  must  be  approximately 
constant;  that  pitch  must  be  accurate  and  the  tone  constant 
during  the  time  it  is  sounded ;  and  that  there  is  grave  danger 
of  identifying  the  tones;  the  mode  of  energizing  the  vibrating 
medium  becomes  a  delicate  matter.  Many  forms  of  appara¬ 
tus  are  ruled  out  because  they  have  some  obstacle  to  effective 
energizing. 

We  therefore  recommend  that  only  such  apparatus  be  used 
as  will  enable  the  experimenter  to  produce  in  rapid  succession 
two  tones  which  are  practically  alike  in  all  respects  except 
pitch. 

6.  Timbre.  The  richer  the  tones  the  more  opportunity 
there  is  for  discrimination  to  fasten  more  or  less  unconsciously 
upon  some  difference  in  the  character  of  the  tone  as  a  means 
of  identification.  Thus,  two  tuning  forks  fixed  upon  wooden 
resonators  invariably  assume  individual  peculiarities  by 
which  they  may  be  identified ;  two  strings  bowed  in  succession 
are  open  to  the  same  objection.  Even  aside  from  this  error 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


27 


of  identification,  impure  tones  are  probably  more  readily 
distinguished  than  pure,  unless  the  impurity  is  of  such  nature 
as  to  be  distracting,  as  in  a  badly  bowed  string.  This  relatively 
greater  ease  in  discrimination  for  rich  or  impure  tones  is 
probably  due  to  aid  from  other  characters  than  pitch,  and 
therefore  illegitimate.  There  are  two  ways  of  dealing  with 
it:  one  is  to  use  a  selective  resonator,  e.g.,  A  Koenig  or  a  Helm¬ 
holtz  resonator,  or  a  water  resonator;  the  other  isto  transmit 
the  vibration  through  a  common  medium,  e.g.,  by  telephone. 
The  telephone  acts  remarkably  well  as  a  selecting  instrument, 
when  used  as  in  ordinary  telephoning,  and  the  timbre  of  the 
tone  produced  in  the  single  receiver  becomes  quite  uniform, 
when  the  sound  comes  from  approximately  uniform  sources, 
but  the  tone  is  not  as  pure  as  when  heard  from  the  resonator 
directly. 

In  view  of  these  facts  we  recommend  that  the  test  be  made 
with  the  purest  tone  available.  As  far  as  we  know  now,  this 
is  best  produced  by  an  unmounted  tuning  fork  reenforced  and 
purified  by  means  of  a  selective  resonator. 

7.  Resonance.  The  sound  is  most  favorable  for  pitch 
discrimination  when  it  is  just  loud  enough  to  be  clearly  heard 
without  effort.  Loudness  depends  chiefly  upon  the  resonance 
of  the  mounting  and  the  surroundings  of  the  vibrating  body. 
It  is  largely  in  the  reenforcement  that  the  tone  gets  its  indi¬ 
vidual  character;  and  the  increased  resonance  usually  results 
in  increased  richness  of  tone,  which  is  a  source  of  most  serious 
disturbance  in  this  test. 

If  a  single  individual  is  to  be  tested,  a  tuning  fork,  for  ex¬ 
ample,  may  be  held  close  to  the  ear  with  good  result  without  a 
resonator.  For  tones  lower  than  75  vd.  the  fork  thus  pre¬ 
sented  should  have  hard  rubber  disks,  about  8  cm.  in  diameter, 
mounted  on  the  outside  of  each  prong.  Such  disks  strengthen 
the  tone  satisfactorily.  But,  for  the  ordinary  work,  with 
tones  near  the  middle  of  the  register  we  recommend,  as  in 
6  above,  the  use  of  the  selective  resonators  with  good  tuning 
forks  unmounted. 

8.  Danger  of  Identification.  One  of  the  most  insinuating 
and  persistent  obstacles — one  most  frequently  overlooked — 


28 


C.  E.  SEASHORE. 


is  the  possibility  of  identifying  one  or  both  of  a  pair  of  tones 
by  other  means  than  pitch  difference  pure  and  simple.  The 
commonest  means  of  identification  are  timbre  (purity)  loud¬ 
ness,  characteristic  difference  in  facility  of  handling,  and  loca¬ 
tion  of  the  sounding  body.  The  situation  is  doubly  compli¬ 
cated  by  the  fact  that  if  the  observer  merely  imagines,  or  has 
an  illusion  to  the  effect,  that  he  can  identify  a  tone  by  one  of 
these  accessories,  this  is  just  as  fatal  to  the  test  as  if  he  actually 
did  identify.  And  it  is  further  aggravated  by  the  fact  that 
the  more  effort  we  make  to  secure  the  desired  uniformity,  e.g., 
absolute  equality  in  intensity  of  tone,  the  more  of  a  temptation 
we  set  the  observer  for  pouncing  upon  this  as  a  means  of 
identification.  And,  worst  of  all,  the  identification  may  work 
itself  out  subconsciously,  and  indeed  it  ordinarily  does,  with¬ 
out  the  observer  being  aware  that  the  accessory  factors  play 
any  role,  in  the  estimation  of  pitch. 

For  these  reasons  we  are  frequently  forced  to  discard  appa¬ 
ratus  which  is  reliable  in  itself  and  may  have  other  advantages. 
Our  general  solution  is  to  get  as  much  uniformity  as  possible 
without  making  it  constant,  e.g.,  the  intensity  of  a  tone  is 
kept  approximately  uniform  by  placing  the  successive  forks 
at  approximately  the  same  point  before  the  resonator.  But 
there  is  a  constant  slight  variation  which  cannot  be  predicted 
or  verified.  The  same  applies  to  timbre,  duration,  mode  of 
presentation,  etc.  The  observer  should  understand  that 
although  these  factors  are  kept  fairly  uniform,  they  are 
not  constant  and  that  he  can  find  no  means  of  identifica¬ 
tion  in  them  because  they  vary  fortuitously  within  small 
limits.  The  apparatus  must  therefore  be  constructed  and 
manipulated  so  that  this  condition  can  be  carried  out,  i.e., 
the  accessory  variation  shall  be  the  very  minimum,  but  the 
observer  shall  have  the  positive  instruction  that  the  varia¬ 
tions  are  not  peculiar  to  any  one  tone.^ 

^  An  illustration  of  this  difficulty  is  found,  e.g.,  in  using  an  automatic  hammer  to 
strike  the  string  or  fork.  The  hammer  produces  more  uniform  intensity  than  we  can 
produce  by  a  stroke  of  the  hammer  in  the  hand;  but  after  a  few  trials  the  observer 
will  detect  some  constant  peculiarity  of  that  stroke,  and  from  that  moment  the  test 
is  vitiated.  And  even  if  the  observer  does  not  detect  any  difference  the  chances  are 
that  he  will  be  influenced  subconsciously  by  automatism  in  the  direction  of  identifying 
tones. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


29 


We  therefore  urge  that  no  test  be  undertaken,  or  record 
accepted,  unless  such  precaution  has  been  taken  with  refer¬ 
ence  to  apparatus,  method,  and  efficiency  in  manipulation  as 
to  guarantee  that  this  danger  of  identifying  one  of  two  tones 
falsely  has  been  ruled  out. 

B.  Apparatus  Rejected. 

As  stated  above,  a  monograph  on  the  availability  and  the 
reliability  of  the  instruments  which  have  been  used  in  this 
test  is  in  preparation  and  will  be  published  with  measurements 
in  detail.  Each  instrument  is  tested  in  several  respects  by 
means  of  the  tonoscope,  which  makes  ready  and  accurate 
measurement  of  all  instruments  by  the  same  means  to  the 
accuracy  of  ±.02  vd.^  The  measurements  have  been  carried 
far  enough  to  lead  us  to  reject,  for  our  present  purpose,  the 
reed,  the  piston  pipe,  the  bottle  (tone  variator),  the  siren, 
and  the  string.  All  of  these  are  available  for  rough  work  and 
each  has  some  superior  feature  which  may  justify  it  for  some 
special  purpose.  We  must,  however,  await  the  publication  of 
the  details  of  the  examination  before  assigning  each  to  its 
place.  In  the  meantime  any  one  who  is  engaged,  or  proposes 
to  engage  in  research  with  any  of  these  instruments,  may  ob¬ 
tain  available  information  by  corresponding  with  the  writer. 

For  our  present  purpose,  all  these  instruments  are  rejected 
(i)  because  they  do  not  give  a  sufficiently  pure  tone,  and  (2) 
because,  under  the  conditions  ordinarily  employed,  they  are 
not  sufficiently  accurate. 

We  urge  that  no  serious  research  be  undertaken  in  pitch 
discrimination  unless  the  experimenter  either  finds  authorita¬ 
tive  standardization  of  his  instrument  on  record  or  himself 
undertakes  careful  tests  on  the  instrument  before  using  it. 
This  is  a  commonplace  rule  in  psychology  but  it  is  as  fre¬ 
quently  violated  as  it  is  commonplace. 


1  This  is  in  rapid  reading.  For  finer  adjustment  than  =*=.02  vd.  it  is  more  conveni¬ 
ent  to  use  the  beat  method. 


30 


C.  E.  SEASHORE. 


C.  Apparatus  Recommended. 

In  view  of  the  above  and  other  considerations  we  recom¬ 
mend  as  the  best  available  and  most  serviceable  apparatus,  a 
set  of  twelve  unmounted  tuning  forks,  a  Koenig  adjustable 
resonator,  and  a  simple  sounding  rod. 

The  forks  best  suited  for  the  purpose  are  of  the  grade  marked 
22807  the  catalogue  of  Max  Kohl,  Chemnitz,  i,  S.,  Germany, 
and  will  be  known  as  the  “standard  pitch  discrimination 
set.”  The  set  includes  two  standard  and  ten  increment  forks. 
They  are  tuned  to  the  accuracy  recommended  in  Sect,  i 
above,  for  the  increments  recommended  in  Sect.  4  above  at 
the  standard  recommended  in  Sect.  3  above.  They  may  be 
imported  duty  free  for  about  $41.00.  The  same  set  of  forks 
untuned  (all  tuned  to  435  vd.)  may  be  imported  duty  free  for 
about  $34.00.^ 

A  cheaper  and  smaller,  yet  serviceable,  grade  of  forks  is 
advertised  as  No.  1730  in  the  catalogue  of  the  C.  H.  Stoelting 
Co.,  Chicago,  and  maybe  obtained  tuned  approximately  the 
same  as  the  above  set  for  about  $18.00.  The  same  forks 
may  be  obtained  untuned  for  about  $12.00. 

It  is  essential  that  the  forks  shall  be  fairly  heavy,  and  of 
uniform  size  and  shape  (except  for  tuning)  and  of  good  material 
and  workmanship.  There  are  many  styles  and  grades  of 
forks  on  the  market  which  would  answer  the  purpose. 

The  resonator  is  a  stock  piece  of  physical  apparatus, 
marked  in  the  catalogues  “Koenig  adjustable  resonator, 
miMa^”  and  may  be  imported  duty  free  for  about  $6.50.2 

For  a  sounder,  use  i  inch  square  rod  covered  by  very  heavy 
soft  rubber  tube  and  fastened  in  a  horizontal  position  firmly 
to  some  heavy  metal  support,  so  that  the  forks  can  strike  on 
one  edge  of  the  rod. 


1  These  forks  are  14.5  cm.  long,  with  prongs  9.5  mm.  wide  and  5  mm.  thick,  and  per¬ 
fectly  uniform  in  shape. 

*  In  lieu  of  this  a  serviceable  resonator  may  be  improvised  by  taking  a  graduate  or 
a  plain  glass  tube  about  ten  inches  long  and  i  J  inches  in  diameter  and  pouring  water  into 
it  until  it  is  tuned  to  the  right  pitch.  Or,  a  brass  tube  may  be  cut  to  the  proper  length 
and  one  end  corked.  Such  devices  give  a  good  quality  of  tone  but  it  is  difficult  to  get 
the  tone  loud  enough  for  a  large  room. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


31 


An  opaque  screen  should  be  provided  to  prevent  the  obser¬ 
ver  from  seeing  any  movements  of  the  experimenter. 

D.  Directions  for  Tuning. 

Since  the  experimenter  must  at  all  times  be  ready  to  test  and, 
if  necessary,  correct  the  tuning  of  the  forks ;  and  since  the  differ¬ 
ence  in  price  is  considerable,  it  is  generally  a  good  plan  to  buy 
the  untuned  forks. 

Raise  the  pitch  of  a  fork  for  each  of  the  ten  increments  by 
filing  equally,  symmetrically  and  squarely  on  the  ends  of  the 
two  prongs — not  on  the  side  of  the  prong  as  is  usually  done. 
Time  by  counting  beats  between  the  filed  fork  and  the  stand¬ 
ard.  For  final  tests  count  the  beats  for  as  long  a  period  as 
they  can  be  heard.  As  one  cannot  count  more  than  three 
beats  per  second  with  certainty  the  5vd.  fork  may  be  tuned 
from  the  3vd.,  the  8  vd.  from  the  5vd.,  etc..  Avoid  the  sources 
of  error  mentioned  above  and  following,  e.g.,  temperature, 
force  of  the  blow,  the  place  of  striking,  etc.  In  order  to 
reduce  the  effect  of  sympathetic  vibrations  from  one  fork 
upon  the  others  hold  the  forks  before  the  resonator  as  far 
apart  as  may  be  compatible  with  audibility  of  the  beats. 
Test  to  the  accuracy  recommended  in  Section  i  above. 

II.  Precautions  to  be  Observed  in  the  Tests. 

A.  With  Reference  to  Apparatus. 

I .  Temperature.  Use  each  of  the  two  standards  alternately 
for  short  periods,  and  hold  all  forks  with  fingers  near  the  end 
of  the  stem  of  the  fork. 

The  pitch  of  a  fork  falls  by  .00011  vd.  for  each  degree  cen¬ 
tigrade  of  rise  in  temperature,  according  to  Lord  Rayleigh. 
Larger  differences  than  this  are  quoted  by  experimenters, 
but  it  is  probable  that  the  effect  of  the  temperature  varies  with 
the  pitch,  size,  form,  etc.,  of  the  fork;  perhaps  also  differently 
with  means  and  extremes  of  temperature.  A  435  vd.  fork 
just  taken  from  boiling  water  is  more  than  4  vd.  lower  in 
pitch  than  the  same  fork  just  taken  from  ice.  This  error  is. 


32 


C.  E.  SEASHORE. 


however,  practically  eliminated:  (i)  by  keeping  all  the  forks 
in  the  same  atmosphere,  and  (2)  by  using  the  two  standards 
alternately  to  reduce  the  cumulative  effect  of  heat  from  strik¬ 
ing  and  from  contact  with  the  hands,  and  (3)  by  holding  all 
forks  near  the  end. 

2.  Position  of  the  Blow.  Hold  the  fork  so  that  it  strikes  the 
sounder  at  the  middle  of  the  prong  and  squarely  on  the  side. 

A  blow  near  the  middle  of  the  prong  starts  the  prong  to 
vibrate  most  favorably — faster  and  more  regularly  than  when 
struck  either  at  the  tip  or  at  the  shoulder.  An  extensive 
series  of  tests  with  one  fork  gives  the  result:  middle,  434.38 
vd. ;  tip  434.22  vd.  The  blow  at  the  middle  of  the  prong  gives 
the  best  quality  of  tone. 

Ideally,  both  prongs  should  be  snapped  so  as  to  start 
synchronously  in  true  phase;  but  this  is  impracticable,  there¬ 
fore  we  adopt  the  plan  of  striking  only  one  prong,  but  under 
uniform  conditions.  The  vibration  frequency  of  the  fork  is 
irregular  until  the  two  prongs  vibrate  symmetrically. 

3.  Force  of  the  blow.  Strike  the  sounder  uniformly  with 
as  light  a  blow  as  will  produce  a  distinctly  audible  tone  through 
the  resonator. 

A  light  stroke  produces  the  smoothest  tone,  a  tone  that 
is  most  favorable  for  true  pitch  discrimination,  and  a  tone 
that  remains  uniform  for  relatively  the  longest  period;  a 
strong  blow  produces  a  harsh  and  changing  tone  and  injures  the 
forks.  The  blow  should  be  a  light  tap  with  free  rebound,  in 
order  that  the  initial  impetus  given  the  prong  may  not  be 
modified  by  continuous  pressure  or  repeated  contact. 

4.  The  Sounder.  Make  sure  that  the  sounder  is  soft, 
well  rounded  and  firm,  with  a  minimum  of  resonance. 

A  springy  sounder  prevents  the  proper  rebound  of  the  fork. 
Any  harshness  or  other  unpleasantness  in  the  thud  is  likely 
to  serve  as  a  distraction,  coming  as  it  does  just  at  the  moment 
attention  is  to  be  focussed. 

5.  Adaptation  Period.  Allow  at  least  one  second  after 
striking  before  presenting  the  fork  before  the  resonator. 

Even  under  favorable  circumstances,  the  first  sound  of 
the  fork  is  rough,  and  the  vibration  frequency  varies  until 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


33 


the  two  prongs  vibrate  symmetrically.  This  makes  it  inad¬ 
visable  to  sound  a  fork  resting  on  a  resonator,  by  striking 
or  blowing. 

6.  The  Resonator.  Suspend  the  resonator  so  that  it  can 
vibrate  freely;  present  the  fork  quickly  and  uniformly  by 
bringing  it  straight  toward  the  mouth  (not  from  the  side)  of 
the  resonator,  so  that  the  upper  end  of  the  side  of  one  prong 
covers  the  opening;  withdraw  it  in  the  same  line. 

If  the  resonator  were  laid  on  a  solid,  e.g.,  a  table,  that  body 
would  add  a  disturbing  resonance.  Presenting  the  fork  from 
the  side  gives  a  rough  edge  to  the  resonator  tone  and  may 
give  a  clue  to  identification  of  forks.  A  quick  and  firm  move¬ 
ment  of  the  hand  insures  a  clear  cut  beginning  and  end  of  the 
tone.  Ordinarily  the  fork  should  be  held  as  close  to  the  reso¬ 
nator  as  it  can  be  without  any  danger  of  touching;  yet  it 
is  possible  to  hold  it  so  close  that  a  recognizable  change  in 
quality  of  the  tone  is  produced. 

The  wooden  resonator  is  discarded  because  it  has  a  very 
rich  and  variable  accessory  resonance. 

7.  Testing  the  Forks.  Test  the  forks  frequently  and  keep 
record  of  the  changes  made  in  a  given  set  of  forks.  Small 
forks  like  these  may  change  vibration  frequency  by  handling. 
Hard  and  irregular  striking  is  probably  the  greatest  source  of 
the  derangement  of  forks.  A  tuning  fork  should  be  handled 
like  a  tuned  string, — with  care.  This  is  especially  true  of  the 
lower  forks  which  represent  the  small  increments.  Wherever 
accurate  measurements  are  made,  the  lower  forks  should 
be  tested  frequently.  In  testing,  all  the  variables  must  be 
eliminated.  No  fork  should  be  filed  until  it  is  perfectly  clear 
that  it  is  faulty,  and  then  only  after  its  relations  to  the  rest  of 
the  series  has  been  determined. 

B.  With  Reference  to  Procedure. 

I.  Intensity.  Make  the  two  tones  equally  loud — just 
so  loud  that  they  can  be  heard  distinctly  without  effort. 

One  of  the  most  serious  obstacles  we  encounter  in  this  test 
is  the  effect  of  intensity  or  loudness  upon  pitch.  An  immature 


34 


C.  E.  SEASHORE. 


observer  is  likely  to  identify  high  and  strong  to  some  extent. 
A  more  developed  or  trained  observer  may  reverse  the  associ¬ 
ation  and  show  a  tendency  to  judge  the  weak  tone  high.  For 
this  reason,  various  contrivances  have  been  designed  to  secure 
uniformity  in  the  intensity  of  tones.  We  here  recommend  that 
the  experimenter  shall  practice,  and  simply  trust  his  own  ear 
and  hand  for  approximate  uniformity.  If  a  fork  is  sounded, 
either  too  weak  or  too  strong,  the  trial  should  be  repeated.  This 
method  is  adopted  because  it  prevents  the  observer  from 
attaching  importance  to  heard  intensity  differences.  When 
mechanical  contrivances  are  used  to  produce  uniformity  in 
intensity,  the  observer  either  hears  or  fancies  he  hears  a 
difference  which  is  consciously  or  unconsciously  taken  as  a 
cue  for  the  identification  of  the  fork. 

Extensive  experiments  show  (i)  that  both  trained  and  un¬ 
trained  observers  may  be  influenced  by  intensity  in  their 
pitch  judgment;  (2)  that  although  there  is  a  tendency  among 
the  untrained,  especially  the  ignorant,  to  judge  the  loud  tone 
the  higher,  it  may  work  either  way;  (3)  that  the  same  individual 
may  show  one  tendency  at  one  time  and  the  reverse  at  another; 
(4)  that  for  trained  observers  the  two  tendencies  are  about 
equal ;  and  (5)  that  the  tendency  is  more  serious  for  large 
than  for  small  intensity  differences.  Introspection  shows 
that  this  confusion  rests  largely  on  motor  tendencies  or 
motor  images.  We  associate  high  and  strong  with  strain — 
the  reversal  can  in  some  cases  be  traced  to  a  correction,  con¬ 
scious  or  unconscious,  based  on  knowledge  of  this  danger. 

Experiments  show  that  the  just  perfectly  clearly  perceptible 
tone  is  most  favorable  for  accurate  results.  It  is  ordinarily 
purer  than  a  stronger  tone  and  favors  concentration.  Experi¬ 
menters  must  guard  against  a  very  common  tendency,  usually 
unconscious,  to  facilitate  the  discrimination  by  making  the 
tones  loud;  and  untrained  observers  usually  desire  (unwisely) 
a  loud  tone. 

2.  Duration.  Sound  each  tone  about  i  second.  The 
most  favorable  duration  of  tone  is  about  \  second.  This 
cannot  be  obtained  in  a  simple  method  of  manipulation;  and 
the  variation  with  duration  from  \  sec.  to  i  sec.  is  not  large. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


35 


The  ratios  found  by  experiment  are:  |  sec.,  73  per  cent;  | 
sec.,  82  per  cent;  ^  sec.,  84  per  cent;  and  i  sec.,  82  per  cent. 
We  may  therefore  content  ourselves  with  as  short  a  tone  as 
can  be  produced  consistently  and  economically  with  clear¬ 
ness  and  uniformity.  In  a  practiced  experimenter  it  ap¬ 
proaches  one  second,  and  this  should  be  kept  constant. 
Here  again  both  the  experimenter  and  the  observer  have  a 
tendency  to  crave  a  longer  duration. 

For  most  accurate  work,  in  which  duration  is  a  factor  to 
be  varied,  or  is  otherwise  important,  mount  a  revolving  disk 
in  front  of  the  mouth  of  the  resonator.  Control  the  speed 
of  the  disk  and  cut  slits  in  appropriate  sectors  to  regulate 
the  duration  of  tone  and  the  time  interval  between  the  two 
tones.  In  this  case  it  is  necessary  to  have  one  resonator  for 
each  fork.  The  fork  may  be  held  by  the  hand  in  the  usual 
way.  This  also  has  the  advantage  of  forcing  the  trials  in 
rapid  succession  and  that  favors  the  discrimination. 

3.  Time  Interval.  Hold  one  fork  in  each  hand  and  strike 
them  in  rapid  succession ;  then  present  them  to  the  resonators 
so  as  to  make  the  time  interval  between  the  two  tones  about 
one  second. 

Discrimination  for  successive  stimuli  always  involves  the 
memory  element.  The  curve  of  tonal  memory,  as  is  well 
known,  is  a  parabolic  curve  showing  that  the  accuracy  of 
memory  falls  off  very  rapidly,  immediately  after  the  first 
second  of  interval.  But  for  intervals  from  ^  sec.  to  i  sec. 
there  is  practically  no  difference,  as  is  shown  by  the  follow¬ 
ing  ratios:  t'g  sec.,  80  per  cent;  i  sec.,  75  per  cent;  \  sec., 
81  per  cent;  ^  sec.,  78  per  cent;  and  i  sec.,  75  per  cent.  It 
is  therefore  important  that  the  time  interval  be  kept  fairly 
constant  and  that  it  should  not  exceed  i  sec.  The  most 
favorable  interval  may  depend  in  part  on  temperament  and 
training  of  the  observer. 

4.  Order.  Determine  the  order  of  presentation  of  the 
higher  and  lower  forks  by  chance;  use  keys  prepared  before¬ 
hand  by  tossing  a  coin.  Modify  the  “chance  order”  of  the 
key  so  that  there  shall  be  no  more  than  three  trials  of  the 
same  order  in  succession. 


36 


C.  E.  SEASHORE. 


If  two  forks  of  the  same  pitch  are  sounded  in  rapid  succes¬ 
sion  some  have  a  tendency  to  call  the  second  higher,  others 
lower.  This  error  is  eliminated  by  alternating  the  order  of 
the  standard  and  the  compared  forks  in  this  chance  order. 

It  is  important  that  this  order  should  be  determined 
objectively.  On  account  of  the  community  of  ideas  and  a 
natural  tendency  to  anticipate,  arbitrary  choice  of  order 
by  the  experimenter  would  lead  to  guessing  “what  he  will 
do,”  and  expectation,  which  would  influence  the  judgments 
very  seriously. 

5.  Uniformity.  Avoid  identifiable  uniformity.  Many  de¬ 
vices  are  available  for  securing  uniformity  automatically. 
Thus,  a  pair  of  electrically  driven  forks,  with  necessary  con¬ 
tact  may  be  used,  as  the  resonator  does  not  speak  to  the 
accessory  sound.  Or,  if  the  accessory  sounds  are  considered 
disturbing,  the  forks  at  the  resonator  may  be  driven  “tan¬ 
dem”  by  another  pair  of  forks  in  a  distant  room.  The 
electrically  mounted  forks  may  be  held,  unmounted,  in  the 
hand.  Automatic  hammers  may  be  so  mounted  on  the  forks 
as  always  to  strike  the  fork  in  the  same  place  and  manner 
and  with  the  same  degree  of  force.  The  forks  may  be  so 
mounted  that  they  swing  automatically  into  position  before 
the  resonator.  A  resonator  may  be  mounted  permanently 
before  each  of  the  automatically  struck  or  electrically  driven 
forks.  The  duration  and  the  interval  may  be  regulated  by 
a  rotating  disk  or  pendulum. 

These  and  many  other  devices  have  been  tried  with  the 
general  result  that  all  except  the  last  (the  regulation  of  dura¬ 
tion  and  time  interval)  have  been  rejected.  It  required  more 
skill  to  operate  one  of  these  devices  safely  than  to  follow  the 
simple  plan  recommended.  The  ever  present  and  practi¬ 
cally  insurmountable  danger  is  that  of  identification  of  a 
tone  by  some  permanent  character  other  than  pitch. 

6.  Fatigue.  Adapt  the  length  of  the  test  to  the  endur¬ 
ance  of  those  "■''sted. 

A  test  of  this  sort  is  novel  and  requires  continuous  con¬ 
scious  effort  and  is,  therefore,  surprisingly  “fatiguing.”  The 
ear  itself  does  not  fatigue  in  the  same  sense  as  the  eye  fatigues. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


37 


but  the  test  requires  an  unusual  concentration  of  attention, 
and  therefore  causes  a  general  exhaustion. 

Extensive  experiments  on  this  specific  problem  show:  (i) 
that,  even  through  the  most  severe  continuous  and  unin¬ 
terrupted  strain  for  two  hours,  a  normal,  reliable,  adult 
observer  (a)  feels  no  fatigue  or  strain  in  the  ear,  and  (b) 
shows  no  progressive  loss  of  keeness  of  discrimination;  (2) 
that  there  are  marked  periodic  fluctuations  in  capacity 
which  usually  correspond  to  felt  distraction,  ennui,  or  lack 
of  effort;  (3)  that  what  is  generally  known  as  fatigue  in  this 
experiment  is  primarily  an  unjustifiable  feeling  of  restless¬ 
ness  or  blaseness  coming  from  the  habit  of  change  and, 
secondarily,  discomfort  from  position;  (4)  that,  in  normal 
observers,  the  discrimination  tends  toward  automatism  and 
becomes  easier  so  far  as  effort  is  concerned  during  uninter¬ 
rupted  progressive  adaptation ;  (5)  that  in  some  persons  the 
strain  brings  on  a  headache;  (6)  that  the  test  is  far  more 
straining  on  the  person  who  is  not  familiar  with  it  than 
one  who  is;  (7)  that  after  extreme  exertion  there  sometimes 
follows  a  reaction  in  the  form  of  a  feeling  of  exhaustion, 
especially  if  the  observer  has  worked  in  a  continuous  "heat” 
unconscious  of  his  bodily  self;  and  (8)  that  in  such  an  endur¬ 
ance  test  good  results  are  obtainable  with  ease  in  proportion 
to  the  absence  of  distraction.  In  short  the  strain  of  the  test 
is  "wearing”  on  the  observer  and,  although  the  progressive 
adaptation  is  favorable  to  the  ease  and  accuracy,  it  is  diffi¬ 
cult  to  secure  continued  application  for  long  periods. 

Therefore  with  primary  children  the  test  should  not  be 
carried  beyond  ten  or  fifteen  minutes  of  continuous  testing 
at  a  time.  With  grade  and  high  school  children,  a  half- 
hour  test  is  most  favorable,  and  even  with  adults  two  half- 
hour  tests  are  more  favorable  than  a  one  hour  test. 

7.  Attention.  Secure  the  most  favorable  form  of  atten¬ 
tion,  the  secondary  passive;  and  favor  economic  distribution 
of  attention  by  proceeding  rapidly  and  regularly. 

It  is  all  important  that  the  observer  should  trust  the  pri¬ 
mary  impressions,  and  that  systematic  warning  should  be  given 
in  such  a  way  as  to  sustain  the  most  favorable  form  of  an 


38 


C.  E.  SEASHORE. 


attention  wave.  The  variation  of  a  fraction  of  a  second 
from  the  time  at  which  a  stimulus  is  legitimately  expected 
is  likely  to  modify  the  record.  In  a  test  of  this  sort  it  is 
always  assumed  that  the  judgment  is  made  under  the  con¬ 
ditions  of  maximum  efficiency  and  attention. 

8.  The  Charge.  Impress  the  individuals  or  groups  to  be 
tested  with  the  seriousness  of  the  test  and  their  accountability 
for  every  judgment. 

There  is  always  a  certain  amount  of  lethargy  in  a  group 
of  individuals,  and  the  group  feeling  tends  to  lessen  individual 
responsibility.  It  is,  therefore,  necessary  that  a  very  specific 
charge  shall  be  made  to  the  group  at  the  beginning  of  the  test. 
Call  attention  to  individual  responsibility,  the  personal  nature 
of  the  record,  the  significance  of  attention,  the  demand  of  ab¬ 
solute  integrity  etc. — and  do  it  with  a  vim.  Be  specific  and 
firm.  A  charge  of  that  sort  may  lower  the  average  record 
for  the  group  very  materially.  We  must  always  assume  that 
an  effective  charge  has  been  made. 

9.  The  Judgment.  Always  require  the  form  of  judg¬ 
ment  which  is  characteristic  of  the  method  of  right  and  wrong 
cases,  i.e.,  the  observer  is  limited  to  two  judgments  (higher 
or  lower);  or,  if  the  third  judgment  (equal)  is  allowed,  the 
records  of  that  equal  judgment  must  be  distributed  in  accord¬ 
ance  with  the  rules  of  the  method  of  right  and  wrong  cases. 

This  rule  is  made  mandatory  by  the  fact  that  (i)  the  illusion 
of  difference  is  very  insistent  and  (2)  that  there  is  no  close 
correlation  between  different  degrees  of  certainty  and  actual 
difference  near  the  threshold.  We  know  rightly  with  a  fair 
degree  of  certainty  whether  or  not  we  hear  a  sound,  or  whether 
it  is  strong  or  weak,  but  not  so  with  pitch  of  sound.  We  have 
distinct  convictions  that  we  hear  difference  in  pitch  often 
when  there  is  no  difference  and  when  the  difference  is  below 
the  threshold. 

III.  Classification  and  Order  of  Tests. 

All  tests  may  be  divided  into  (i)  preliminary  and  (2)  final. 
Each  of  these  may  be  made  as  (i)  group  or  (2)  individual 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


39 


tests.  The  preliminary  group  test  is  heterogeneous,  the 
final  homogenous.  The  heterogeneous  group  test  is  one  in 
which  a  group  of  individuals,  e.g.,  a  grade,  a  class,  a  type, 
or  a  community,  is  tested  en  hloc  for  the  purpose  of  classify¬ 
ing  the  individuals  in  the  group  as  a  preliminary  to  the  final 
test,  or  for  rough  and  rapid  permanent  classification.  The 
homogenous  group  is  one  in  which  the  individuals  have  been 
grouped  together  on  the  basis  of  approximate  equality  in 
pitch  discrimination,  as  determined  by  some  preliminary 
test.  For  the  final  test  we  may  employ  a  well  recognized 
method;  for  the  latter  it  is  necessary  to  use  an  improvised 
method.  Both  are  described  in  the  following  section. 

The  extent  and  order  of  the  test  should  be  determined  in 
view  of  the  purpose  to  be  served,  time  available,  means  at 
hand,  etc.  For  thorough  examination  of  large  numbers  we 
recommend  the  following  order  of  procedure: 

1.  A  one-hour  test  of  the  heterogeneous  grouph 

2.  A  one-hour  “final”  test  of  homogeneous  divisions  of 
the  group,  based  upon  the  classification  obtained  in  i. 

3.  Homogeneous  group  tests  with  full  introspection,  ad 
libitum. 

4.  Individual  interview,  check  trials,  and  extended  “final” 
individual  test. 


IV.  Directions  for  Tests 

A.  Preliminary.  When  the  first,  or  only  test  is  to  be 
made  on  a  heterogeneous  group,  set  aside  one  hour  of  time  for 
the  actual  test.  Supply  each  individual  with  a  cross  ruled 
paper,  designating  the  vertical  columns  by  numbers  from  i 
to  20,  and  the  horizontal  columns  by  the  letters,  A  to  J.  Call 
the  increments  A,  B,  C,  D,  etc.,  beginning  with  the  largest. 
Thus,  A  denotes  a  difference  of  30  vd.;  B,  23  vd.,  C,  17  vd.. 


^  The  limit  to  the  numbers  of  persons  that  may  be  tested  at  one  time  depends  upon 
a  number  of  considerations  such  as  discipline  under  control,  the  loudness  of  the  tone,  the 
homogeneity  of  interest  in  the  group,  the  acoustic  qualities  of  the  room,  the  skill  of  the 
experimenter,  etc.  Under  favorable  circumstances,  one  can  readily  handle  a  group  of 
200  to  300  persons  at  one  time  for  a  preliminary  test. 


40 


C.  E.  SEASHORE. 


etc.  Illustrate  to  the  group  how  the  forks  are  sounded  and 
what  is  meant  by  pitch. 

Then  give  instructions  to  the  following  effect:  I  will 
sound  two  tones  in  quick  succession.  You  are  required  to 
record  whether  the  second  is  higher  or  lower  than  the  first. 
There  will  always  be  a  difference  in  the  pitch,  but  if  you  can 
not  hear  it,  you  must  guess.  If  the  second  tone  Is  higher, 
record  H;  it  If  is  lower,  record  L. 

Give  a  few  preliminary  trials  in  which  all  are  required  to 
speak  L  or  H  instead  of  writing  It.  Follow  this  by  some  illus¬ 
tration  of  differences  in  intensity  until  all  distinguish  clearly 
between  intensity  and  pitch.  Urge  them  to  trust  the  first 
impression,  and  warn  them  not  to  despair  when  they  feel 
in  doubt.  Suggest  that  they  keep  their  eyes  closed  when 
listening.  Explain  that  before  each  trial  you  will  give  them 
warning  by  designating  the  square  in  which  they  are  to 
record.  Thus:  column  i.  A;  B;  C;  etc.,  and  in  the  same 
manner  in  succeeding  columns. 

In  determining  the  order  of  the  sounds,  follow  a  key  made 
out  beforehand,  as  directed  above,  to  determine  whether  the 
standard  shall  be  sounded  first  or  second.  This  operation 
of  the  law  of  chance  should  be  explained  to  prevent  guessing 
or  probabilities.^ 

All  being  prepared,  give  without  interruption  one  set  of 
trials,  A  to  J,  and  then  allow  a  one-half  minute  rest. 
Take  as  many  sets  of  trials  as  the  time  permits.  A  skillful 
experimenter  can  take  about  eighteen  sets  in  an  hour.  If  the 
record  Is  not  to  be  used  in  any  important  way,  read  off 
the  key  slowly,  after  completing  five  sets,  and  require  each 
individual  to  check  errors  by  drawing  a  bold  line  through  the 
letter  which  is  wrong.  The  experimenter  must  adapt  methods 
to  conditions.  For  example,  each  observer  may  be  allowed 
to  check  his  own  record  or  they  may  be  required  to  exchange. 
The  experimenter  must  also  use  his  judgment  In  deciding 
whether  or  not  it  is  necessary  to  counter-check  the  records. 


1  It  should  be  explained  in  particular  that  if  the  coin  has  fallen  head  up,  e.g.,  two 
times  in  succession  the  probability  is  still  exactly  equal  for  head  and  tail. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


41 


Request  each  observer  to  make  note  of  anything  that  may 
aid  in  the  interpretation  of  the  record  and  its  significance. 
For  certain  purposes  it  is  desirable  to  have  systematic  informa¬ 
tion  about  each  individual,  as  regards  musical  training, 
attainments,  environment,  appreciation,  etc.  The  follow¬ 
ing  questionnaire  has  been  found  serviceable. 

Name  . Age.  .  .  .Date . Hour.  .  .  .Class . 

Please  give  as  specific  and  detailed  information  as  possible  in 

regard  to  your: 

I.  Musical  Training 

1 .  In  public  schools 

2.  Private  vocal  lessons  (when,  where,  how  long,  etc.) 

3.  Private  instrumental  lessons  (when,  where,  how  long,  etc.) 

II.  Musical  Environment 

1.  Instruments  in  your  home,  and  their  use 

2.  Musical  encouragement  at  home  (trained  voices  in  family) 

3.  Opportunities  for  hearing  music  of  any  sort  (specific) 

III.  Musical  Expression 

1.  Favorite  selections  you  can  sing  (by  ear?  by  note?) 

2.  Favorite  selections  you  can  play  (by  ear?  by  note?  instru¬ 
ments?) 

3.  Singing  or  playing  in  public  (parts,  occasions,  etc.) 

IV.  Enjoyment  of  Music  (What  Actually  Appeals  to  You) 

1.  Vocal  (solo,  quartette,  chorus,  opera,  popular  songs,  classics, 
religious,  secular) 

2.  Instrumental  (solo,  symphony,  band,  etc.) 

3.  Characteristic  effects  of  music  (mental,  physical) 

We  begin  with  a  large  step  because  that  gives  the  observer 
a  clear  grasp  of  the  nature  of  the  difference  and  starts  him 
with  confidence  in  his  judgment.  We  take  a  set  at  a  time 
(vertical  column)  instead  of  giving  successive  trials  on  the 
one  step  (horizontal  column),  because  the  short  set  makes  a 
favorable  distribution  of  strained  attention.  We  take  the 
whole  set  of  ten  steps  each  time  primarily  because  we  are 
dealing  with  a  heterogeneous  group  of  observers,  and  second¬ 
arily  in  order  to  approach  the  threshold  under  uniform  con¬ 
ditions.  Twenty  sets  really  amount  to  twenty  trials,  each 


42 


C.  E.  SEASHORE. 


set  being  a  trial  to  see  how  far  down  on  the  scale  of  incre¬ 
ments  the  observer  can  hear  correctly.  Given  the  range  of 
increments,  and  the  allotted  time,  the  task  is  to  secure  as 
many  trials  as  may  be  needed  for  a  fairly  reliable  record 
within  this  minimum  period  of  time. 

The  computation  of  the  records  must  be  left  to  the  ex¬ 
perimenter.  Run  through  the  checked  records  and  place  a 
tally  mark  for  each  set  in  the  horizontal  column  above  the 
one  in  which  the  first  error  occurred  in  a  set.  The  completed 
tally  will  then  show  the  distribution  of  the  thresholds  for 
sets  in  terms  of  the  smallest  increment  for  and  above  which 
all  judgments  are  correct. 

Compute  the  medians.  The  formula  for  the  median  may 
be  found  in  Titchener’s  Instructors'  Manual,  Quantitative, 
pp.  8,  9  and  361. 

Supplement  this  numerical  record  by  notes  on  internal 
evidence  in  the  record,  such  as  modes,  progressive  changes, 
confusion,  mistakes  in  record,  etc.,  and,  when  fully  justified, 
enter  a  numerical  estimate  of  a  correction.  The  record  thus 
corrected  should  be  more  reliable  than  the  original. 

For  the  series  of  threshold  values  thus  obtained  (before 
the  correction,  if  any  is  made)  the  standard  deviation,  or  the 
probable  error,  or  both,  should  be  calculated.  For  direc¬ 
tions  see  same  reference  to  Titchener,  pp.  9-1 1.  But  these 
calculations  are  very  laborious.  For  ordinary  work  we 
therefore  recommend  as  a  measure  of  variation  in  the  record 
the  use  of  the  mean  variation  (m.v.)  computed  as  follows: 
Regard  the  difference  between  successive  steps  as  equal 
psycho-physic  steps  and,  with  the  increment  which  is  nearest 
to  the  median  as  a  base,  multiply  the  number  of  cases  which 
are  one  step  from  the  base  by  i,  the  number  that  are  two 
steps  away  by  2,  the  number  that  are  three  steps  away  by  3, 
etc. ;  divide  the  sum  of  these  products  by  the  total  number 
of  cases  (sets). 

This  record  on  a  heterogeneous  group  should  be  regarded 
(i)  merely  as  a  preliminary  to  more  accurate  tests  in  homo¬ 
geneous  divisions  of  the  group,  or  (2)  as  a  rough  record, 
serviceable  when  exactness  is  not  required.  It  is  a  “quick 
method.” 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


43 


B.  Final.  Take  in  one  division  all  observers  who  have  ap¬ 
proximately  the  same  threshold,  as  determined  by  prelimin¬ 
ary  test;  use  one,  two,  three,  or  even  four^  increments,  accord¬ 
ing  to  the  closeness  of  the  grouping,  and  proceed  by  the 
method  of  right  and  wrong  cases  to  find  the  threshold  for 
75  per  cent  correct  cases. 

C.  Individual  Tests.  In  making  individual  tests  the  pre¬ 
liminary  procedure  here  recommended  for  the  group  may 
be  followed ;  but  in  most  cases  it  is  better  to  make  a  quick 
informal  skirmish  to  find  the  approximate  threshold  and  then 
proceed  by  the  method  of  right  and  wrong  cases,  using  a 
single  increment. 


V.  Interpretation. 

A.  Distribution  of  the  Records  for  a  Group. 

I.  The  Normal  Curve.  The  normal  curve  of  distribu¬ 
tion  of  the  records  for  a  preliminary  group  as  determined  by 
the  preliminary  method  described  above  is  shown  in  Fig.  i, 
(From  data  collected  by  George  H.  Mount  and  Franklin  O. 
Smith.)  The  curve  is  based  on  the  records  of  781  under¬ 
graduate  university  students,  296  men  and  485  women. 

In  the  interpretation  of  this  curve  it  should  be  remembered 
that:  (i)  most  of  the  records  (581)  are  in  terms  of  the  “aver¬ 
age  of  the  middle  third, ”2  in  place  of  the  median;  (2)  no  cor¬ 
rection  of  this  has  been  made  on  the  ground  of  internal 


1  For  a  first  homogeneous  test  on  large  numbers  it  is  convenient  to  take  three  groups 
as  follows;  Group  A,  including  all  those  whose  thresholds  lie  above  9  vd.;  Group  B, 
including  all  whose  threshold  falls  between  9  vd.  and  3  vd.,  inclusive;  and  Group  C, 
including  all  whose  threshold  lies  below  3  vd.  Later,  for  extended  tests, these  groups; 
may  be  subdivided. 

As  a  rule,  one  hundred  trials  in  each  instrument  is  the  very  minimum  for  the  num¬ 
ber  of  trials  that  may  be  trusted.  Increments  for  which  the  record  shows  less  than 
65  per  cent  or  more  than  90  per  cent  right  cases  should  not  be  used. 

2  The  average  of  the  middle  third  was  obtained  by  rejecting  the  lowest  third  and  the 
highest  third  of  the  observations  and  counting  the  “average  of  the  middle  third.” 
For  183  cases  in  which  the  median  and  the  average  of  the  middle  third  were  both  com¬ 
puted,  the  former  gave  7.4  and  the  latter  7.2  as  a  central  value.  The  results  are  there¬ 
fore  quite  comparable. 


44 


C.  E.  SEASHORE. 


evidence  in  the  individual  record;^  (3)  no  increment  of  less 
than  I  vd.,  or  more  than  30  vd.,  was  used;  (4)  the  division  of 
groups  for  the  curve  is  made  midway  between  increments; 
(5)  the  observers  were  without  practice  (the  test  was  made  in 
an  hour)  in  this  test,  but  all  accustomed  to  psychological 
experiments;  and  (6)  the  observers  represent  a  select  body, 
as  admission  to  the  University  represents  a  survival  process. 

This  curve  may  be  regarded  as  a  norm.  It  may  be  ex¬ 
pressed  conveniently  in  a  mathematical  equation. 


% 


3.  Comparison  with  Other  Sensory  Discrimination.  There 
are  two  characteristic  features  in  the  curve :  the  decided  skew¬ 
ness,  and  the  absence  of  a  well  defined  mode.  These  together 
indicate  that  there  is  a  wide  range  of  difference  in  the  capacity 
of  individuals.  There  is  no  mode  or  unit  which  may  be  said 
to  represent  a  norm.  Instead  of  seeking  an  average,  or  norm, 
we  must  seek  to  establish  some  serviceable  division  into 
classes. 


1  Such  corrections  always  lower  the  result.  They  may  be  found  necessary  in  from 
5  to  10  per  cent  of  the  cases. 


MEASUREMENT  OF  PITCH  DISCRIMINATION 


45 


In  this  respect  this  curve  differs  from  curves  representing 
sensory  discrimination  in  other  factors;  e.g.,  visual  or  tactual 
discrimination  for  linear  magnitudes,  form,  or  size;  weight 
and  pressure;  and  direction  and  intensity  of  sound. 

4,  Extremes.  Individuals  are  found  who  can  detect  a 
small  fraction  of  difference  in  pitch ;  these,  if  any  in  this  group, 
are  here  included  with  i.  The  marvelous  keenness  claimed 
by,  and  reported  in  the  biography  of,  certain  musicians  has 
seldom  been  verified.  A  verified  threshold  of  less  than  .3  vd. 
is  rare.  On  the  other  hand  defective  tone  discrimination 
gradually  shades  off  into  tone  deafness.  Such  cases  are  in¬ 
cluded  in  30  -4-  in  the  above  curve.  Tone  deafness  probably 
prevails  to  the  same  extent  as  color  blindness;  but  we  have 
no  satisfactory  statistics  of  either. 

B.  Reliability. 

1.  The  Mean  Variation.  In  the  preliminary  test  we  have 
the  m.  V.  as  a  measure  of  validity  In  the  record.  Fig.  2  (from 
Franklin  O.  Smith)  shows  the  distribution  of  the  m.v.  In  a 
group  of  records  as  figured  according  to  the  directions  given 
above.  The  figures  at  the  base  denote  m.v. ;  those  in  the 
side  of  the  curve,  per  cent  of  error.  It  ranges  roughly,  between 
.5  of  a  step  and  2.5  of  a  step.  A  m.v.  of  i  .0  step  or  less  indicates 
an  entirely  safe  record ;  a  m.v.  above  2.0  steps  proves  the  record 
worthless;  between  these  extremes  the  reliability  is  roughly 
In  inverse  ratio  to  the  magnitude  of  the  m.v.  The  m.v.  should 
therefore  help  us  in  determining  the  necessity  of  verifying  a 
record  by  further  tests.  The  standard  deviation  and  the  prob¬ 
able  error  If  calculated,  of  course,  serve  the  same  purpose  in  a 
more  exact  way. 

2.  Internal  Evidence  and  Notes.  In  the  case  of  a  large 
m.v.  It  Is  imperative  to  examine  the  distribution  of  the  obser¬ 
vations.  Two  extreme  types  are  shown  together  in  Fig.  3 
(from  F.  Z.  Wheeler).  Each  is  based  on  34  “sets”  of  trials. 
The  average  of  the  middle  third  is  the  same  In  the  two  records, 
namely  5.3  vd.  The  median  is  also  approximately  the  same, 
but  the  m.v.  for  A  is  i .  i  and  for  B,  3.6.  Thus  the  record  for  A 


46 


C.  E.  SEASHORE. 


is  fairly  reliable,  but  for  B  utterly  unreliable.  But  the  record 
shows  that  B  has  8  out  of  a  possible  34  records  right  on  f  vd. 
If  he  has  no  capacity  in  pitch  discrimination  the  probability 
is  I  in  1024  that  he  should  get  a  record  on  |  vd.  in  one  set, 
i.e.,  the  whole  column  right,  by  pure  chance.  And  from  what¬ 
ever  point  in  the  set  pure  chance  operated,  the  chances  of 
getting  successive  judgments  right  decreases  in  geometrical 
ratio.  Thus,  if  his  actual  threshold  were  really  above  5  vd. 
the  chance  that  he  would  get  5  vd.  (and  all  above)  right  is 


i  A  &  I  It  li  7.4  78  Z.  2.6  26  e.9 

Fig.  2 


1 :  2 ;  3  vd.,  1 :  4;  2  vd.,  1:8;  i  vd.,  i  :i6;  and  ^  vd.,  1 132. 
Eight  records  on  ^  vd.  in  34  cases  therefore  almost  amounts 
to  certainty  that  B  can  hear  a  difference  of  ^  vd.  A  correction 
must  therefore  be  made,  inserting  the  record  ^  vd.  as  one  mode 
and  the  probable  threshold. 

But  B’s  remarkable  record  may  be  due  to  one  of  at  least  two 
different  causes.  A  glance  at  the  original  record  shows  that  all 
the  poor  records  were  made  in  the  first  part  of  the  test  To¬ 
ward  the  end  he  is  almost  perfect,  which  of  course  means  that 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


47 


in  the  first  part  of  the  test  there  was  a  lack  of  understanding 
of  something.  This  adds  even  more  assurance  to  our  esti¬ 
mate  of  the  I  vd.  threshold.  Another  possible  explanation 
of  such  a  record,  except  for  this  last  fact  of  progressive  change, 
is  that  B  had  a  good  ear  but  was  a  “scatterbrain.”  It  might 
also  mean  that  there  was  some  other  disturbing  element  either 
subjective  or  objective  in  the  test,  but  in  no  case  would  we 
have  any  doubt  about  the  quality  of  the  ear. 

In  accepting  records  we  must  always  bear  in  mind  the  num¬ 
erous  sources  of  error — objective,  in  the  apparatus  or  in  the 


% 


manipulation  by  the  experimenter;  or  subjective,  due  to 
ignorance,  inattention,  lack  of  effort,  etc.  The  longer  a 
careful  experimenter  works  at  it  the  more  he  learns  of  how 
conditions,  apparently  irrelevant,  may  play  an  important  r61e. 
With  patient  practice  we  can  learn  to  conduct  the  test  on  a 
group  so  that  each  individual  record  receives  more  than 
mechanical  treatment.  One  must  play  over  the  full  gamut 
of  errors  before  he  attributes  a  peculiarity  in  the  record  to 
the  ear. 


48 


C.  E.  SEASHORE. 


3.  ''Final"  Test.  In  following  the  method  proposed 
for  the  “final”  test,  with  an  individual  or  a  homogeneous 
group,  the  reliability  depends  upon  the  number  of  trials, 
but  first  and  last  upon  the  favorableness  and  the  accuracy 
of  the  control  of  the  conditions  under  which  the  judgment  is 
rendered. 

4.  Proportionality  of  Increments.  It  should  not  be  assumed 
that  the  perceptibility  of  the  difference  in  pitch  varies  directly 
with  the  difference  in  the  pitch  of  the  two  tones.  Tones  that 
blend,  such  as  the  fundamental  and  the  major  third  or  fifth 
are  readily  confused.  But,  within  the  range  of  30  vibrations, 
at  this  pitch,  the  variation  is  probably  fairly  direct. 

5.  Difference  vs.  Direction.  The  threshold  for  the  percep¬ 
tion  of  difference  is  of  course  different  from  the  threshold  for 
the  perception  of  direction  of  the  difference.  While  the  former 
is  the  principle  which  operates  in  nearly  all  musical  apprecia¬ 
tion,  the  latter  is  usually  taken  as  the  measure  of  pitch  dis¬ 
crimination,  partly  because  it  measures  a  capacity  in  musical 
expression  but  chiefly  because  it  can  be  determined  more 
accurately  than  the  former. 

6.  Relative  Central  Values.  In  estimating  the  value  of  the 
threshold  we  must  take  into  consideration  (i)  the  form  of 
judgment  upon  which  it  is  based,  (2)  the  step  counted,  (3) 
the  kind  of  central  value  employed,  and  (4)  the  apparent 
plasticity  of  the  threshold,  illustrated  in  7,  8,  and  9,  below. 

The  reasons  for  selecting  the  form  of  judgment  here  recom¬ 
mended  and  rejecting  the  threshold  which  depends  upon  sub¬ 
jective  certainty  have  been  stated  in  Sect.  II  A  9  above. 

We  have  chosen  to  count  the  last  judgment  preceding  the 
first  mistake  in  a  set  because  we  have  found  empirically  that 
it  comes  nearest  to  the  actual  threshold  of  just  perceptible 
difference,  when  a  sufficient  number  of  sets  of  trials  have  been 
taken.  Granting  that  this  step  is  subliminal  it  would  of  course 
yield  right  judgments  half  of  the  time  by  pure  chance,  and  the 
same  is  true  of  all  steps  below  it,  each  considered  by  itself. 
On  the  other  hand,  it  is  well  known  that  in  this  form  of  judg¬ 
ment  errors  will  occur  above  the  threshold  for  various  reasons. 
The  step  we  have  adopted  seems  to  strike  a  fair  mean  between 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


49 


these  two  tendencies.  Furthermore  it  represents  a  definitely 
definable  procedure. 

For  central  values  we  have  at  our  command  different  kinds 
of  averages,  modes  and  medians.  The  ordinary  average  or 
arithmetical  mean  is  out  of  question,  since  the  large  incre¬ 
ments  would  count  too  heavily  in  proportion  to  the  small. 
The  average  of  the  middle  third  largely  obviates  this  difficulty 
and  has  the  advantage  of  an  average;  it  is  therefore  quite 
satisfactory.  The  mode  is  not  always  representative,  but  the 
mode,  or  modes,  in  the  distribution  of  a  set  of  observations 
must  always  be  taken  into  consideration :  we  count  it  a  sec¬ 
ondary  central  value,  often  most  significant.  The  calculated 
median  (not  the  median  of  plain  inspection)  is  the  most 
representative  value  that  we  can  use  because  it  eliminates  the 
extremes  and  gives  a  fair  distribution  of  the  most  charac¬ 
teristic  values. 

The  relation  of  the  median  as  obtained  in  the  preliminary 
test  to  the  record  by  the  method  of  right  and  wrong  cases,  as 
obtained  in  the  “final”  test  has  not  yet  been  worked  out  to 
a  satisfactory  degree  of  certainty.  A  preliminary  estimate  of 
the  relationship  (by  F.  Z.  Wheeler)  makes  the  median  to  be 
not  far  from  equal  to  75  per  cent  of  right  cases.  For  225  cases 
the  median  for  the  one  hour  preliminary  test  is  3.3;  the  thres¬ 
hold  for  75  per  cent  correct  cases  is  3.1  in  an  individual  test 
immediately  following.  Data  are  being  collected  for  a  direct 
comparison  of  the  two  central  values  in  the  same  observations. 

7.  The  Cognitive  vs.  the  Physiological  Threshold.  In  sen¬ 
sory  discrimination  of  this  sort  we  may  speak  of  two  thres¬ 
holds:  the  physiological,  which  is  set  by  the  limits  of  capacity 
in  the  end  organ;  and  the  cognitive,  which  is  set  by  cognitive 
limitations.  Theoretically  we  always  aim  to  reach  the  physio¬ 
logical  threshold,  but  practically  we  often  fall  short  of  this 
and  find  a  cognitive  limit;  i.e.,  a  higher  threshold  due  to  lack 
of  information,  best  form  of  attention,  interest,  effort,  etc. ; 
or  to  disturbances  of  some  sort.  Usually  inspection  of  a  record 
or  observations  made  in  the  test  enable  us  to  tell  whether  or 
not  we  have  reached  the  physiological  threshold.  It  cannot 
be  judged  by  any  single  rule,  although  a  small  m.v.  with  one 


C.  E.  SEASHORE. 


SO 

well  defined  mode  are  pretty  sure  indications.  This  distinc¬ 
tion  is  of  greatest  importance  in  classification,  and  in  the 
theory  of  training. 

8.  The  Illusion  of  Difference.  One  of  the  most  bewildering 
experiences  of  a  trained  observer  is  to  find  that  he  is  subject 
to  very  strong  illusions  of  difference.  Such  illusions  are  com¬ 
mon,  in  mild  form,  with  reference  to  all  liminal  values,  but 
here  it  is  very  pronounced  and  almost  unbelievable. 

Closely  related  to  this  illusion  is  the  fact  that  the  feeling  of 
certainty  in  our  judgment,  near  the  threshold,  is  not  as  reli¬ 
able  here  as  in  most  other  sensory  discrimination.  An  exten¬ 
sive  record  of  the  degree  of  certainty  by  a  trained  observer,  on 
a  scale  of  five,  for  a  long  series  of  judgments  shows  that  there 
is  no  close  correlation  between  the  degree  of  certainty  felt  and 
the  actual  correctness  of  the  judgment. 

Very  much  depends  upon  the  direction  of  expectant  atten¬ 
tion.  Listening  to  two  tones  physically  of  the  same  pitch  one 
can  make  either  tone  seem  higher  or  lower  at  will.  This 
introduces  a  very  serious  difficulty  in  the  experiment.  It  is 
exceedingly  difficult  to  keep  the  observer  from  directing  his 
expectant  attention  in  favor  of  one  tone  or  the  other.  Great 
ingenuity  and  watchfulness  on  the  part  of  the  experimenter  is 
necessary  in  order  to  keep  the  observer  as  neutral  as  possible. 

9.  Plasticity  of  the  Threshold.  Except  for  the  very  keen 
mind  with  a  keen  ear,  the  threshold  is  not  a  sharply  fixed 
limit.  In  the  first  place  there  are  so  many  obstructions  to  the 
most  favored  hearing  that  we  always  expect  fluctuations  in 
judgments  and  do  not  assume  that  we  have  reached  the  abso¬ 
lute  physiological  limit,  but  rather  a  normal  approximation 
which  may  be  used  as  a  norm.  For  most  of  our  purposes  it  is 
quite  as  serviceable.  On  the  other  hand,  it  is  not  unwarranted 
to  suppose  that  the  surface  of  frequency  for  a  given  set  of 
records  actually,  though  in  exaggeration,  represents  something 
of  the  flexibility  of  the  physiological  threshold. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


51 


C.  The  Tonal  Register. 

I.  The  Normal  Curve.  Our  tests  have  been  made  at  one 
level,  a,  435  vd.  What  knowledge  have  we  of  the  relation  of 
this  level  to  other  levels?  Records  have  been  published  on 
individual  musicians,  notably  Luft  and  Stumpf,  whose  dis¬ 
crimination  is  exceedingly  fine,  but  a  record  of  more  nearly 
average  observers  is  more  directly  applicable  for  us.  Fig,  4 


Fig.  4 


(from  unpublished  MS  by  H.  G,  Schaefer)  is  a  representation 
of  the  average  for  eleven  good  observers  in  the  laboratory 
showing  the  relative  sensitiveness  to  differences  in  pitch  to 
different  levels  within  the  tonal  register.  From  100  vd.  to 
about  500  vd.,  the  least  perceptible  difference  is  almost  a 
constant  in  terms  of  vibration  frequency  and  a  geometric 
ratio  in  terms  of  tone  interval;  but  both  ends  of  the  curve 


52 


C.  E.  SEASHORE. 


deviate  from  this  ruled  In  general  the  individual  curves  are 
of  the  same  type  as  the  composite,  regardless  of  whether  the 
threshold  is  high  or  low. 

For  our  present  purpose  the  curve  shows  (i)  that  measure¬ 
ments  made  within  the  middle  of  the  tonal  register  are  com¬ 
parable  and  convertible  in  terms  of  vibration  frequency  (2) 
that  a  moderate  increment  taken  above  the  standard  is 
practically  equal  to  one  taken  below,  in  terms  of  vibration 
frequency;  and  (3)  that  435  vd.  represents  approximately 
the  most  sensitive  level  in  terms  of  the  tone  interval. 

2.  Gaps.  However,  certain  individuals  have  “gaps,” 
i.e.,  parts  of  the  register  for  which  they  are  less  sensitive  than 
the  normal  curve  would  indicate;  or,  they  may  even  be  tone 
deaf  for  a  few  notes,  although  keen  in  the  hearing  of  other  notes. 
In  such  islands  of  partial  tone  deafness  the  person  hears  the 
tone  just  as  distinctly  as  elsewhere  and  feels  that  he  can  dis¬ 
cern  pitch  difference,  but,  upon  being  tested,  he  finds  that  he 
is  more  or  less  helpless.  The  writer  has  such  a  gap  from 
64  vd.  to  45  vd.,  but  it  took  a  variety  of  crucial  tests  to  con¬ 
vince  him  of  it  on  account  of  the  prevailing  illusion  of  differ¬ 
ence  at  this  point.  Statistics  in  regard  to  the  extent  and 
frequency  of  this  phenomenon  are  being  collected.  Such 
gaps  furnish  most  excellent  opportunity  for  study  of  the 
traits  of  defective  tone  hearing  by  one  who  has  a  keen  ear 
for  other  parts  of  the  register. 

D.  Correlation  of  Pitch  Discrimination  with  other  Possible 
Factors  in  '^Musical  Ability. 

Correlations  have  been  worked  out  for  musical  education, 
environment,  heredity,  ability  in  performing,  tonal  fusion, 
appreciation,  singing,  rhythm,  auditory  imagery,  auditory 
memory,  etc.,  but  it  has  not  been  found  advisable  to  include 
results  of  that  work  in  this  preliminary  report.  Reports  on 
this  subject  will  be  published  soon  by  G.  H.  Mount  and 
■others. 


‘  Luft  and  Meyer  (or  Stumpf)  did  not  find  such  deviation  at  the  ends. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


S3 


E.  Practice,  Age  and  Sex 

I.  Practice.  The  above  correlation  may  be  summed  up 
in  the  statement  that  pitch  discrimination  is  an  inborn 
capacity  which  ordinarily  reveals  itself  in  full  force  without 
special  training  just  as  the  psychophysic  capacity  in  auditory 
acuity  or  visual  acuity  reveals  itself  spontaneously. 

The  problem  of  training  is  one  of  great  practical  signifi¬ 
cance.  It  presents  a  fertile  field  for  experiment  in  educational 
psychology.  Under  our  direction  the  problem  has  been 
approached  through  the  following,  among  other,  kinds  of 
practice  series  in  which  intensive  and  exclusive  training  in 
pitch  discrimination  has  been  given  by  employing  the  ‘‘final” 
test  above  in  a  prolonged  series  of  tests  {i.e.,  the  training  was 
gained  from  the  continuous  tests) :  with  (i)  persons  with  good 
ear  and  (a)  musical  education  and  (b)  no  musical  education; 

(2)  persons  with  average  ear  and  (a)  musical  education  and 
(b)  no  musical  education;  and  (3)  persons  with  inferior  ear 
and  (a)  musical  education  and  (b)  no  musical  education. 
These  tests  are  made  both  on  adults  and  on  children,  and  both 
by  individual  and  group  training. 

At  this  preliminary  stage,  the  following  general  conclusions 
may  be  stated: 

(1)  When  the  proximate  physiological  threshold  has  been 
reached,  practice  is  of  no  avail. 

(2)  So  long  as  a  cognitive  threshold  prevails  there  is 
prospect  of  improvement  by  practice  to  the  extent  that  the 
cognitive  is  above  the  physiological,  limit. 

(3)  This  improvement  is  usually  very  rapid,  often  immedi¬ 
ate  and  can  usually  be  traced  to  the  acquisition  of  knowledge, 
through  experience  or  information  about  what  pitch  is,  as 
distinguished  from  other  attributes  of  tones. 

(4)  In  the  majority  of  cases  it  is  possible  for  the  ingenious 
experimenter  to  discover  the  proximate  physiological  thres¬ 
hold  to  a  fair  degree  of  certainty  in  a  well  planned  half-hour 
individual  test,  or  in  one  heterogeneous  and  one  homogeneous 
group  test  of  one  hour  each;  and,  for  most  of  the  cases  in 
which  this  fails,  the  same  tests  demonstrate  positively  that 
the  threshold  is  only  cognitive. 


54 


C.  E.  SEASHORE. 


(5)  The  possibility  of  reaching  the  physiological  limit  in 
a  single  test  depends  to  but  very  slight  extent  upon  whether 
or  not  the  person  tested  has  had  musical  education;  it  is 
mainly  a  matter  of  expert  skill  and  ingenuity  on  the  part  of 
the  experimenter. 

(6)  Ordinarily  musical  education  is  not  effective  as  a 
means  of  improving  pitch  discrimination.  (From  work  of 
H.  S.  Buffum,  F.  Z.  Wheeler  and  George  H.  Mount). 

As  an  illustration  of  the  degree  of  finality  which  may  be 
obtained  in  a  preliminary  test  we  may  turn  to  Figure  5  (from 
H.  S.  Buffum).  Dr.  Buffum  experimented  on  twenty-five 
eighth  grade  pupils  in  a  grammar  school  room.  He  first  made 
a  fifteen  minute  individual  test  of  each  pupil  and  classified 
them  on  this  basis  into  three  groups  with  modes  at  3,  8,  and 
17  vd.  respectively.  The  object  was  twofold:  (i)  to  deter¬ 
mine  the  effect  of  practice  and  (2)  to  determine  the  success  of 
the  preliminary  examination.  For  this  purpose  he  gave  them 
twenty  forty-minute  periods  of  training. 

The  training  consisted  in  taking  records  by  the  method  of 
right  and  wrong  cases.  The  figures  at  the  bottom  of  the  curve 
denote  days,  those  on  the  side  per  cent  of  right  cases;  the 
fourth  curve  is  a  combination  of  the  three.  The  results 
show  (i)  that  for  no  group  is  there  any  evidence  of  improve¬ 
ment  with  this  practice,  and  (2)  that  all  except  two  children 
remained  throughout  the  whole  practice  series  within  the 
group  to  which  they  had  been  assigned.  Of  these  two,  one 
who  had  been  assigned  to  group  III  was  immediately  found  to 
belong  in  group  I  as  there  had  been  a  failure  to  understand 
the  preliminary  test;  and  the  other,  although  retained  in 
group  II,  proved  really  to  be  near  the  dividing  line  and  could 
have  been  classified  in  group  III.  Evidently  the  physiological 
threshold  had  been  reached  in  twenty-four  of  the  twenty-five 
cases  in  the  preliminary  test. 

The  capacity  for  appreciation  of  music  Is  partially  inborn 
and  partially  the  result  of  training.  Thus,  in  judging  the 
quality  of  an  instrument  or  a  voice,  the  expert  hears  and 
observes  differences  and  peculiarities  that  entirely  escape  the 
untrained  ear;  and  all  differences  In  so-called  quality  or  tim- 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


55 


Fig. 


56 


C.  E.  SEASHORE. 


bre  of  tones  are  reducible  to  pitch.  But  such  hearing 
represents  a  complex  process  of  interpretation,  which  can  be 
mastered  only  after  extensive  training.  The  mere  detection 
of  pitch  difference  is,  on  the  other  hand,  a  simple  process 
requiring  only  the  slightest  amount  of  training. 

Now,  to  the  extent  that  we  control  and  simplify  conditions 
so  as  to  make  our  test  a  simple,  sensory,  direct  comparison  in 
regard  to  which  there  can  be  no  misunderstanding,  we  have  a 
valid  test  of  pitch  discrimination  which  approaches  the  phy¬ 
siological  limit. 

2.  Age.  A  preliminary  estimate  of  data  on  the  variation 
of  pitch  discrimination  with  age  may  be  summed  up  in  the 
following  general  conclusions: 

(1)  The  physiological  limit  is  probably  lowest  in  early 
childhood  but  remains  fairly  constant  up  to  maturity. 

(2)  In  a  bright  child  with  a  good  ear  the  physiological 
limit  can  be  established  for  all  practical  purposes  as  early  as 
the  age  of  five. 

(3)  The  slight  inferiority  of  record  which  we  find  in  a 
group  of  young  children  over  the  record  of  a  group  of  adults 
is  due  to  cognitive  difficulties,  which  are  not  in  the  nature  of  a 
lack  of  skill  in  the  sense  of  a  slowly  acquired  ability  but 
rather  due  to  lack  of  knowledge.  The  university  students 
have  every  advantage — musical  education,  maturity  for  reli¬ 
ability  in  observation,  power  of  application,  familiarity  with 
the  experimental  conditions,  etc.,  which  is  quite  enough  to 
account  for  the  superiority  of  their  group  record  over  the 
record  of  a  group  of  children.  There  is  no  such  large  dif¬ 
ference  of  advantage  between  high-school  pupils  and  gram¬ 
mar-school  pupils,  and  their  records  practically  agree. 

3.  Sex.  Pitch  discrimination  does  not  vary  in  any  con¬ 
stant  manner  with  sex.  The  small  oscillating  differences 
shown  in  Fig.  i  are  characteristic. 

F.  Practical  Use. 

I .  In  the  P sychological  Laboratory.  The  main  use  of  this 
measurement  is  of  course  in  the  psychological  laboratory — 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


57 


in  teaching,  and  in  research.  But  the  discussion  of  that  feature 
scarcely  comes  within  the  scope  of  this  report. 

2.  In  the  School  Room.  While  this  is  a  "mental  test,” 
our  report  demonstrates  that  we  are  not  justified  in  using  it 
as  a  general  mental  test,  or  test  of  intelligence,  as  has  often 
been  done.  It  gives  us  a  measure  of  a  specific  and  peculiar 
capacity — probably  dependent  upon  the  structure  of  the  sense 
organ;  and  that  is  a  reason  for  employing  it  in  the  school 
room  in  this  age  of  interest  in  individual  capacity  and  adapta¬ 
tion. 

Suppose  that  we  find  four  children  of  equal  age,  advance¬ 
ment  and  general  ability  sitting  together  and  one  has  a  thres¬ 
hold,  for  pitch  discrimination,  of  ^  vd.,  another  3  vd.,  another 
12  vd.,  and  another  25  vd.  They  are  to  have  singing  lessons. 
How  can  we  group  them  properly  for  this  period?  Nine  years 
ago  the  writer  proposed  the  following  arbitrary  classifica¬ 
tion  as  a  tentative  measure  {Educational  Review,  June  1901) : 

Below  3  vd.:  May  become  a  musician; 

3-8  vd.  :  Should  have  a  plain  musical  education  (singing  in  school 
may  be  obligatory); 

9-17  vd.  :  Should  have  a  plain  musical  education  only  if  special 
inclination  for  some  kind  of  music  is  shown  (singing 
in  school  should  be  optional) ; 

18  and  above:  Should  have  nothing  to  do  with  music. 

This  might  serve  as  a  basis  for  the  adaptation  and  assign¬ 
ment  of  singing  exercises,  or  substitutes  for  singing. 

Exercises  of  this  sort  should  be  a  part  of  the  music  course  in 
school.  They  furnish  the  best  kind  of  mental  discipline; 
they  direct  attention  to  one  feature  in  music  in  a  concrete 
way;  they  stimulate  interest  and  effort  in  observation  and 
right  execution  of  pitch;  and,  incidentally,  they  furnish 
instructive  records  which  may  be  collected  as  a  basis  of  classi¬ 
fication.  Children  are  entitled  to  know  the  facts  thus  learned. 
One  period  set  aside  for  the  interpretation  of  the  records  may 
be  of  untold  value  especially  (i)  to  those  children  who  are  in 
danger  of  having  a  musical  education  forced  upon  them, 
although  they  are  physically  incapable  of  hearing  music  in 


58 


C.  E.  SEASHORE. 


the  true  sense;  and  (2)  to  those  children  who  first  discover  in 
this  test  their  natural  ability  in  this  respect  and  are  stimu¬ 
lated  to  take  an  interest  in  musicd 

3.  In  the  Studio.  The  first  music  lesson  should  be  a  pitch 
test.  There  are  scores  of  other  factors  which  go  to  make 
up  musical  ability,  but  unless  a  person  has  a  good  ear,  he  will 
fail  to  appreciate  and  will  be  unable  to  produce  music  which 
depends  upon  the  ear.  We  often  find  music  students  who 
lack  a  general  interest  in  music  because  they  have  no  “ear. 

A  person  may  have  a  good  ear  and  yet  be  lacking  in  other 
musical  capacities,  for  example,  rhythm,  hearing,  consonance 
and  disonance,  auditory  imagery,  affective  tendencies,  etc. 
Therefore,  this  pitch  test  should  be  followed  up  with  other  tests 
on  musical  capacity,  but  this  is  the  first  and  fundamental.^ 

4.  General  Cautions.  As  this  measurement  constitutes  a 
quantitative  rating  of  a  capacity  of  an  individual  in  such  a 
way  that  it  may  act  as  a  powerful  stimulus  or  an  effective 
deterrent,  we  cannot  be  too  emphatic  in  demanding  that  infor¬ 
mation  about  rating  and  advice  based  upon  it  should  be  given 
not  only  conservatively  but  with  prudence  and  reserve.  In 
one  case  the  rating  may  blast  a  life  ambition,  in  another,  it 
may  be  the  means  of  discovering  the  individual.^ 


^  The  place  for  the  test  is  in  the  first  six  grades.  It  can  readily  be  adapted  to  the 
ability  of  the  children  of  the  different  grades.  Thus  the  test  should  be  short  and  answer 
may  be  made  by  simple  means,  such  as  showing  of  hands  and  counting  the  number  of 
mistakes;  but  for  the  purpose  of  classification  greater  care  must  be  taken.  As  a  rule, 
the  younger  the  child  the  more  necessity  there  is  for  making  the  test  individual. 

^  What  a  blessing  to  a  girl  of  the  age  of  eight,  if  the  music  teacher  would  examine 
her,  and,  if  necessary  say,  “much  as  I  regret  it,  I  must  say  that  you  would  find  music 
dull  and  difficult,  and  I  would  advise  you  to  take  up  some  other  art.”  What  a  blessing 
if  that  child  could  be  started  right;  but  current  theory  and  practice  is  againsther.  There 
is  too  much  faith  in  what  music  lessons  can  do  for  a  person  without  native  capacity.  If 
we  are  to  have  musical  ears,  we  must  be  born  with  them.  That  is  the  probable  finding  of 
current  research. 

®  Among  such  tests  in  progress  at  the  present  time  are  the  following:  the  sense  of 
rhythm,  and  rhythmic  action,  tonal  fusion  (consonance  and  dissonance),  auditory 
imagery,  auditory  memory,  discrimination  for  intensity  of  sound,  and  vocal  repro¬ 
duction  of  a  tone. 

*  The  writer  recalls  the  case  of  a  university  junior  who  had  taken  music  lessons  for 
twelve  years,  but  took  no  real  pleasure  in  it  and  made  but  little  headway.  When  she 
found  that  her  rating  was  12  vd.  she  exclaimed,  “That  is  it.  That’s  what  I  have 
thought,”  and  quit  music. 


MEASUREMENT  OF  PITCH  DISCRIMINATION. 


59 


And  in  such  weighing  of  evidence  we  must  ever  bear  in 
mind  that  there  is  a  compensation  for  this  lack  of  ability  in 
hearing  fine  pitch  differences.  An  inferior  ear  hears  tones  as 
tones,  but  fails  to  hear  small  differences  in  pitch  and  may  fail 
to  hear  the  true  pitch  of  a  clang;  but  this  may  be  an  advantage 
as,  e.g.,  in  listening  to  instruments  out  of  tune  or  inferior 
rendition.  He  may  enjoy  his  own  singing  even  though  he 
cannot  carry  a  tune.  While  such  partial  tone  deafness  pre¬ 
vents  the  critical  and  most  varied  enjoyment  of  music,  it 
permits  and  even  encourages  idealizing  and  undisturbed, 
crude  enjoyment  of  tone  productions  provided  the  individual 
has  some  “music  in  his  soul.” 

We  must  also  distinguish  between  advice  to  possible  musi¬ 
cians  and  to  others  who  may  desire  to  have  some  music  for 
“home  consumption.”  There  is  an  element  of  music  in  the 
bones,  the  drum,  and  the  tambourine.  The  associations  with 
music  are  often  rich  and  valued  in  themselves.  Even  a  bare 
intellectual  familiarity  with  matters  musical  has  its  charm. 
The  words  of  songs  get  a  setting  from  music  even  in  the  un¬ 
musical  ear.  We  must,  therefore,  bear  in  mind  that  pitch 
is  not  the  only  avenue  to  musical  appreciation. 

In  conclusion,  then,  let  us  post  the  following  warnings: 

(1)  A  record  should  not  be  the  basis  for  rating  and  advice 
until  it  represents  the  proximate  physiological  threshold.^ 

(2)  No  classifying  tests  should  be  employed  with  groups 
except  by  persons  who  are  capable  of  taking  proper  experi¬ 
mental  precautions  and  making  a  safe  interpretation. 

(3)  Whenever  possible,  rating  should  be  considered  per¬ 
sonal,  confidential  information. 

(4)  Persons  with  poor  rating  should  not  be  discouraged 
in  their  enjoyment  of  music;  there  is  much  in  music  besides 


On  the  other  hand,  it  should  not  be  supposed  that  the  parties  concerned  always  take 
advice.  The  writer  was  called  in  to  tell  why  the  oldest  of  three  children  in  a  musical 
family  was  not  making  satisfactory  progress  with  her  music;  the  younger  children 
clearly  outclassed  her.  Pitch  test  showed:  boy,  age  ii,  i  vd.;  girl,  age  15,  1.2  vd.; 
girl,  age  19,  13  vd.  Explanation  and  advice  was  given  on  the  basis  of  this  rating,  but 
the  parents  sent  the  oldest  girl  to  a  better  conservatory. 

*  The  cases  left  in  suspense  are  no  worse  off  than  they  have  been  heretofore.  With 
further  patience  they  may  be  reduced. 


6o 


C.  E.  SEASHORE. 


pitch  of  tone,  and  much  enjoyment  of  music  does  not  depend 
upon  the  hearing  of  fine  distinctions  of  pitch. 

(5)  Although  perhaps  the  most  fundamental,  pitch  dis¬ 
crimination  is  only  one  of  a  score  or  more  of  technical  tests 
which,  taken  together,  constitute  a  measure  of  “musical 
ability.”  Conclusions  must  be  limited  to  the  element  tested. 


METHODS  FOR  THE  DETERMINATION  OF  MENTAL 

IMAGERY. 


By  James  R.  Angell. 

Part  I— Examination  of  Methods  in  Use. 

In  few  fields  of  psychological  investigation  has  the  situ¬ 
ation  changed  so  completely  in  the  last  few  years  as  in  that 
covered  by  the  title  of  this  report.  When  the  writer  in  1906 
undertook  to  make  a  comparison  of  the  tests  then  in  use,  the 
literature  relating  to  such  work  was  relatively  circumscribed 
and  the  devices  then  in  vogue  relatively  simple  and  sup¬ 
posedly  fairly  accurate. 

The  author  imagined,  as  did  others,  that  his  task  would 
consist  in  making  a  careful  comparison  of  the  recognized 
tests,  eliminating  untrustworthy  features,  possibly  adding  a 
few  new  ones,  but  at  least  standardizing  the  tests  in  terms 
of  one  another.  Although  this  seemed  a  fairly  large  con¬ 
tract,  it  appeared  to  be  quite  definite  and  was  entered  upon 
with  an  optimistic  spirit. 

Since  that  date  a  large  amount  of  excellent  work  bearing 
upon  the  subject  has  been  produced  and  complexities  have 
been  revealed  previously  little  suspected.  This  development 
was  foreshadowed  by  the  first  investigations  made  by  the 
author  in  1907  and  indicated  in  the  preliminary  report  made 
to  the  association  at  the  annual  meeting  that  year.  In 
attempting  to  compare  the  relative  merits  of  several  famil¬ 
iar  forms  of  procedure,  he  became  convinced  that  the  prob¬ 
lem  was  much  more  baffling  than  had  ordinarily  been  recog¬ 
nized  and  much  broader  in  its  outlook  than  had  been  admitted. 
The  present  situation  is  far  from  satisfactory,  as  will  be  made 
clear  below,  but  the  author  herewith  offers  certain  recom¬ 
mendations  for  tests  in  accordance  with  the  promise  made 
at  the  meeting  of  the  association  in  1909. 


62 


JAMES  R.  ANGELL. 


It  is  not  without  interest  to  remark  in  passing  that  the 
period  during  which  we  have  heard  most  about  imageless 
thought  and  about  the  fallacious  importance  attributed  to 
imagery  in  general,  should  coincide  with  the  period  in  which 
many  of  the  best  and  most  exhaustive  studies  of  imagery 
have  been  made. 

Before  proceeding  to  present  the  recommendations,  it 
will  be  desirable  to  pass  in  critical  review  the  several  forms 
of  procedure  at  present  in  use  in  connection  with  the  study 
of  imagery.  This  survey  is  not  offered  as  exhaustive  of  all 
variations  in  detail.  But  it  includes  the  main  forms  of  which 
the  author  knows,  so  far  as  he  has  found  them  productive. 

The  methods  employed  to  diagnose  imagery  fall  into  two 
main  divisions  (as  regards  their  purpose,  if  not  as  regards 
their  results^);  (i)  objective,  in  which  the  subject  is  set  to 
perform  a  certain  task  so  devised  that  the  results  he  achieves 
will  disclose  forthwith  the  kind  of  imagery  he  uses.  (2) 
Subjective,  in  which  by  various  devices  the  subject  is  given 
tasks  to  perform  which  will  presumably  facilitate  his  ability 
to  discover  and  report  the  imagery  he  uses.  Evidently  the 
first  form  of  test  is  the  ideal  thing,  for,  if  successful,  it  avoids 
the  unreliability  of  merely  introspective  analysis  and  des¬ 
cription.  Objective  methods  may  be,  and  ordinarily  are,  sup¬ 
plemented  with  introspective  analyses,  so  that  combination 
subjective-objective  methods,  rather  than  those  of  purely 
objective  character  are  in  general  to  be  distinguished  from 
the  purely  subjective  modes  of  procedure. 

DIVISION  I.  OBJECTIVE  METHODS. 

A.  One  of  the  earliest  and  still  most  frequently  used  of 
objective  tests  is  that  in  which  material  is  given  to  be  memor- 


^  Several  other  classifications  have  been  proposed  and  a  different  meaning  is  attached 
to  the  classification  here  used  by  Lay,  in  his  monograph  on  Imagery  {Psychological 
Review  Monographs,  vol.  ii,  no.  3),  who,  as  I  understand  him,  makes  the  term  subjec¬ 
tive  apply  to  methods  in  which  the  subject  exercises  his  own  introspective  analyses. 
The  term  objective  he  applies  to  all  methods  in  which  there  is  any  effort  at  experi¬ 
mental  control.  Dr.  M.  R.  Fernald  in  a  forthcoming  monograph  recognizes  three 
groups,  (i)  subjective,  (2)  objective  and  (3)  a  combination  subjective-objective  class. 


MENTAL  IMAGERY. 


63 


ized  visually,  or  aurally,  or  with  the  assistance  of  motor 
activities  as  in  spelling  and  writing.  The  form  in  which  the 
memorizing  is  most  effective  is  assumed  to  indicate  the  pre¬ 
ferred  and  dominant  type  of  imagery. 

This  procedure  has  been  modified  in  various  ways,  e.g., 
by  offering  to  memory  objects,  sounds,  and  words,  the  lat¬ 
ter  designating  sense  experiences  of  the  eye,  the  ear,  the  mus¬ 
cles,  etc.  The  terms  best  remembered  are  again  assumed 
to  indicate  the  ideational  type,  visual  characters  being  best 
remembered  by  a  visualizer,  auditory  characters  by  those 
who  chiefly  employ  auditory  images  and  so  on. 

Tests  of  this  type  may  have  an  undoubted  practical  sig¬ 
nificance  in  connection  with  studies  in  economy  of  learning 
and  permanency  of  retention.  They  may  certainly  be  so 
administered  as  to  show  over  what  sensory  arcs  the  best 
results  may  be  achieved  in  assimilating  information  of  various 
kinds.  They  may  convey  information  as  to  dominant  inter¬ 
ests.  They  also  possess  an  unquestioned  value  as  a  stimulus 
to  intropsection.  But  as  objective  tests  of  imagery,  apart 
from  introspection,  they  have  few  virtues  and  no  reliability. 
For  instance,  a  subject  may  learn  a  series  of  objects  visually 
as  rapidly  as  he  learns  them  from  hearing  their  names  pro¬ 
nounced,  and  yet  his  recall  of  the  object  may  be  in  terms  of 
auditory-motor  words.  He  translates  the  visual  objects  into 
words  and  at  times  recalls  better  such  a  series  than  one  learned 
originally  from  words  themselves.  The  writer  is  himself 
an  illustration  of  this  type.  Were  the  test  employed  to  give 
objective  information  in  such  a  case,  it  would  clearly  result 
in  a  false  conclusion.  Numerous  other  difficulties  of  this 
same  variety  are  met  with  in  the  effort  to  use  the  results 
objectively. 

B.  Methods  of  (j)  Distraction  or  disturbance,  and  {2)  of 
'helps.'  (i)  The  theory  on  which  these  tests  proceed  is 
old  in  experimental  psychology,  but  relatively  new  in  its 
application  to  the  study  of  imagery.  The  distraction  test 
as  used,  for  example,  by  Cohn,i  has  many  variant  forms  and 

^  Zeitschrifl  f.  Psychol,  u.  Physiol.,  1898,  vol.  iv,  p.  161.  Cf.  also  Meumann,  Vor- 
lesungen  z,  EinfUhrung  in  d.  Exper.  Pddagogik,  Leipzig,  1907. 


64 


JAMES  R.  ANGELL. 


has  been  employed  in  combination  with  a  number  of  other 
methods  here  mentioned.  Its  application  may  be  illustrated 
in  the  realm  of  sound. 

If  a  person  who  relies  mainly  upon  auditory  imagery  is 
memorizing  a  series  of  words  presented  visually,  it  is  assumed 
that  a  stimulation  of  the  ear  will  increase  the  difficulty  of 
his  learning  much  more  than  it  does  for  a  learner  of  visual 
type.  Similarly,  distracting  visual  stimuli  will  react  most 
disadvantageously  upon  the  memorizing  of  one  of  visual 
type,  and  motor  activities  of  the  vocal  mechanism  or  the 
hand,  will  most  hamper  one  of  motor  type. 

The  assumption  is  broadly  true  on  the  positive  side;  that 
is  to  say,  users  of  the  corresponding  imagery  are  often  seri¬ 
ously  embarrassed  by  such  distractions,  but  in  practice  it 
is  found  quite  impossible  to  infer,  e.g.,  that  one  who  is  dis¬ 
turbed  by  an  intruding  noise  is  therefore  a  person  who  uses 
auditory  imagery  predominantly,  and  the  amount  of  the  dis¬ 
turbance  caused  is  in  no  wise  regularly  related  to  the  amount 
of  auditory  imagery  employed.  The  general  distraction  of 
attention  produces  anomalies  in  the  results  which  render  the 
method  highly  ambiguous  except  when  conjoined  with  ade¬ 
quate  introspection.  Moreover,  it  is  found  quite  impossible 
in  the  case  of  some  individuals  to  devise  any  distraction 
which  will  measurably  decrease  the  use  of  their  preferred 
forms  of  images,  short  of  such  a  distraction  as  will  preclude 
any  learning  at  all.  Furthermore,  cases  have  been  found 
by  Dr.  M.  R.  Fernald  in  the  Chicago  Laboratory  where  a 
vocal  distraction  has  emphasized  rather  than  impeded  the 
auditory-vocal  imagery  used  in  learning  and  recall.  The 
vocal  distraction  has  on  the  other  hand  proved  very  disturb¬ 
ing  to  the  visual  processes  with  certain  subjects.  In  my 
own  case  such  a  distraction  appears  to  be  effective  not  so 
much  by  its  stoppage  of  the  articulatory  accompaniment  of 
the  learning  (it  stopped  this  very  imperfectly),  but  because 
it  breaks  up  the  associative  processes  of  perception,  so  that 
I  do  not  apprehend  the  meaning  of  the  word  easily  or  cor¬ 
rectly. 

It  may  be  added  in  passing  that  although  relatively  sat- 


MENTAL  IMAGERY. 


65 


isfactory  auditory  and  motor  distractions  have  been  deter¬ 
mined,  equally  satisfactory  visual  distractions  have  not  been 
discovered. 

(2)  The  method  of  helps  is  even  more  ambiguous  in  prac¬ 
tice,  although  equally  simple  and  obvious  in  theory.  The 
commonest  form  of  the  test  is  in  connection  with  such  tests 
as  were  mentioned  under  I  A.  Suppose  several  series  of  dig¬ 
its  are  to  be  learned.  A  person  of  motor  type  would  presum¬ 
ably  be  most  helped  by  being  allowed  to  pronounce  the  dig¬ 
its,  aloud  or  under  the  breath,  or  possibly  by  being  allowed 
to  make  the  movements  of  writing  them.  The  auditory 
imagery  as  judged  by  many  memory  tests  would  presumably 
be  helped  by  a  rhythmic  arrangement  of  material.  Visual- 
izers  might  be  helped  by  arranging  material  in  certain  groups 
or  patterns. 

As  in  the  method  of  disturbance  or  distraction,  the  general 
assumption  underlying  this  program  is  probably  correct,  i.e., 
that  there  are  variations  in  procedure  which  will  assist  par¬ 
ticular  individuals  because  of  their  peculiar  imagery.  But 
the  assumption  as  applied  is  much  too  simple  and  schematic 
to  meet  the  complications  of  actual  mental  life.  For  exam¬ 
ple,  our  experiences  in  the  Chicago  Laboratory  seem  to  show 
that  persons  who  use  a  good  deal  of  visual  imagery  may  be 
quite  as  much  helped  by  rhythmic  arrangement  of  material 
as  audiles,  and  an  occasional  audile  is  disturbed  rather  than 
helped  by  rhythm,  at  least  by  those  imposed  by  the  experi¬ 
menter.^ 

Speaking  well  within  the  mark,  then,  one  may  say  that  the 
methods  of  helps  and  distractions  when  taken  apart  from 
introspection,  are  quite  untrustworthy  as  thus  far  developed. 
Both  are,  however,  extremely  useful  in  stimulating  intro¬ 
spection  by  throwing  into  strong  perspective  the  processes 
actually  employed  in  learning  a  given  material. ^  It  must 

^  The  terms,  visualizer,  audile,  etc.,  are  simply  used  to  indicate  persons  who  in  the 
test  under  discussion  belong  to  these  groupings.  The  ambiguity  of  such  terms  for  gen¬ 
eral  classification  is  dealt  with  at  a  later  point. 

*  Both  may  be  used  either  with  children  or  with  adults  in  a  way  to  throw  valuable 
light  on  the  conditions  practically  desirable  for  learning,  but  these  merits  must  not  be 
confused  with  the  objective  adequacy  of  the  method  for  revealing  imagery. 


66 


JAMES  R.  AN  CELL. 


also  be  clearly  and  emphatically  stated  that  the  objective 
results  of  these  tests  often  afford  most  striking  confirrhation 
of  the  introspections. 

C.  Kraepelin' s  test.  A  test  of  Kraepelin’s  to  which  cer¬ 
tain  writers  have  assigned  objective  value  consists  in  asking 
subjects  to  write  for  five  minutes  lists  of  words  desig¬ 
nating  objects  primarily  characterized  by  color,  in  another 
five  minutes  objects  primarily  referring  to  sound,  etc.  The 
lists  when  compared  are  supposed  to  indicate  the  scale  of  dis¬ 
tribution  for  different  kinds  of  imagery,  the  dominant  type 
being  represented  by  the  most  extended  list.  I  do  not  find 
that  Kraepelin  himself  ever  laid  claim  on  behalf  of  the  test 
to  objective  validity  of  imagery  analysis.  He  speaks  of  it  as 
giving  interesting  and  suggestive  information  about  mental 
organization.^ 

It  undoubtedly  has  some  value  as  indicative  of  verbal 
imagination,  for  the  test  can  be,  and  often  is,  carried  out  by 
subjects  purely  on  the  basis  of  verbal  imagery.  In  my  own 
experiments  it  has  appeared  to  possess,  as  nearly  as  possible, 
no  value  whatever  for  the  objective  determination  of  type,  or 
for  the  objective  ascertainment  of  the  presence  or  absence  of 
any  special  form  of  imagery. 

To  mention  only  one  of  several  ambiguous  cases  illustra¬ 
tive  of  the  difficulties  the  method  presents,  we  may  notice 
that  such  a  word  as  ‘bird’  is  suggestive  of  visual  and  of  audi¬ 
tory  qualities  in  essentially  like  degree,  and  the  presence  of 
such  a  word  in  a  list  of  reactions  would  leave  one  quite  unable 
to  decide  whether  it  indicated  auditory  or  visual  imagery  in 
the  reagent.  It  is  surprising  to  find  how  many  terms  suffer 
from  similar  kinds  of  ambiguity. 

D.  Method  of 'Style.'  The  same  approbation  and  the  same 
criticism  may  be  accorded  the  so-called  method  of  ‘style,’ 
which  is  supposedly  available  for  the  determination  of  types 
through  an  examination  of  the  vocabulary  employed  in  a 
writer’s  works,  especially  when  these  are  of  a  descriptive 
character.  The  method  may  often  give  correct  results  within 


^  Psychol.  Arbeilen,  1895,  vol.  i,  p.  73. 


MENTAL  IMAGERY. 


67 


the  narrow  field  to  which  it  applies,  but  it  is  never  possible 
to  be  sure  of  these  and  the  outcome  is  certainly  misleading 
in  its  indications  in  many  instances^ 

E.  Tests  on  Imagination  Rather  than  Imagery.  Paradox¬ 
ical  as  it  may  sound,  there  are  in  use  several  forms  of  test 
sometimes  used  in  a  purely  objective  way,  which  are  known 
as  tests  of  imagination,  although  little  or  no  imagery  need 
be  actually  involved  in  performing  them. 

The  ‘ink-blot’  test  is  a  case  in  point.  Ink-blots  are  shown 
to  the  subject  and  he  is  asked  whether  the  blot  suggests  any 
object  to  him.  If  he  replies  promptly  and  perhaps  sees  sev¬ 
eral  things  in  the  blot,  he  is  credited  with  an  active  visual 
imagination.  If  he  fails  to  do  so,  he  is  alleged  to  be  deficient 
in  visual  imagery.  The  data  are  too  few  to  say  in  what  degree 
the  actual  possession  of  vivid  and  profuse  visual  imagery  is 
correlated  with  expertness  in  this  class  of  test.  But  one  thing 
is  entirely  certain,  that  persons  may  make  a  very  respectable 
showing  in  the  test  who  employ  a  relatively  slight  amount  of 
visual  imagery. 

These  tests  and  others  like  them  are  really  tests  of  percep¬ 
tual  fertility  rather  than  tests  of  imagery  in  any  proper  sense. 

Summary. 

The  preceding  paragraphs  are  offered  as  showing  conclu¬ 
sively  that  no  purely  objective  methods  of  imagery  analysis 
are  at  present  reliable.  There  may  be  other  tests  of  which 
the  writer  has  no  knowledge  that  satisfactorily  fulfill  the  nec¬ 
essary  conditions.  In  any  event  full  recognition  must  be 
accorded  the  valuable  confirmation  of  introspection  fre¬ 
quently  afforded  by  tests  of  this  type. 

DIVISION  II.  COMPOUND  SUBJECTIVE-OBJECTIVE  METHODS. 

Many  of  the  following  methods  are  at  times  used  purely 
subjectively,  though  they  all  contain  elements  capable  of  use 
for  objective  interpretation.  But,  as  in  the  preceding  group, 

^  Cf.  A.  Fraser,  Amer,  Jour.  Psychol.,  1891,  vol.  iv,  p.  230. 


68 


JAMES  R.  AN  CELL. 


none  of  them  possesses  any  serious  significance  apart  from 
the  introspective  evidence  gained  by  it. 

A.  The  Questionary.  The  method  of  Gal  ton,  modified 
and  elaborated  by  many  subsequent  psychologists,  is  too 
familiar  to  require  extended  description.  Specific  questions 
are  set  which  invite  the  production  of  images  from  each  sense 
department,  and  the  subject’s  introspections  are  recorded. 
Quality,  number,  vividness,  objectivity,  persistency,  controla- 
bility,  etc.,  are  reported  upon. 

Dream  imagery  may  be  treated  in  the  same  way  and  many 
interesting  experiments  have  been  made  on  the  control  of 
dreams,  the  relation  of  dreaming  to  depth  of  sleep  and  so  on ; 
but  the  subject  seems  to  be  a  trifle  aside  from  the  main  pur¬ 
pose  of  this  report  and  will  not  be  further  considered  at  pres¬ 
ent. 

In  the  hands  of  competent  introspectionists  a  good  ques¬ 
tionary  gives  quickly  a  fair  view  of  the  capacities  of  the  indi¬ 
vidual  for  the  voluntary  arousal  of  imagery.  The  method  is 
too  difficult  for  occasional  persons  untrained  in  introspec¬ 
tion.  It  is  probably  rarely  successful  in  informing  us  with 
accuracy  or  certainty  of  the  forms  of  imagery  actually  most 
employed  and  their  manner  of  employment  in  common  men¬ 
tal  tasks.  Moreover,  we  cannot  judge  that  specific  images 
are  entirely  lacking  because  they  are  not  reported  in  replies 
to  a  questionary.  Other  forms  of  test  frequently  bring  out 
images  which  escape  notice  in  the  questionary  method. 

B .  A  ssociation  fro?n  a  Stimulus  Word.  A  series  of  words 
is  shown  or  read  one  at  a  time  and  the  subject  at  once  reports 
the  ideas  called  up  and  the  imagery  involved.  If  the  stim¬ 
ulus  words  are  skillfully  collected,  the  results  are  often  very 
satisfactory  in  the  calling  out  of  various  forms  of  imagery 
and  in  giving  indications  of  the  type  prevailing  for  this  kind 
of  task.  The  reactions  themselves,  as  given  in  words,  are 
often  suggestive,  though  by  no  means  adequate  for  an  objec¬ 
tive  test.  The  test  is  less  significant  for  persons  who  use 
chiefly  word  imagery,  and  it  may  lose  value  still  further  in 
the  case  of  the  'automatic’  reagents  for  whom  a  reaction  word 
comes  solely  and  immediately  as  a  suppressed  enunciation. 


MENTAL  IMAGERY. 


69 


This  is  the  main  limitation  of  the  method,  that  it  tends  to 
magnify  word  imagery.  Of  course  it  gives  no  adequate  indi¬ 
cation  of  the  distribution  of  imagery  in  ordinary  activities. ^ 

C.  Method  of  Letter  Squares.  This  method  has  been 
employed  with  sundry  modifications  by  several  psycholo¬ 
gists  and  in  its  most  frequent  form  is  known  by  Binet’s  name. 
Letters  are  presented  in  a  frame-work  of  squares  so  arranged 
as  to  bring  the  squares  into  vertical  and  horizontal  lines  like 
a^chess-board.  In  the  simplest  form  of  the  test  the  subject 
reads  the  lists  a  certain  number  of  times  visually  and  then 
attempts  to  repeat  them.  Full  introspections  are  invited. 

It  is  commonly  assumed  as  a  matter  of  objective  import 
that  a  visual-minded  person  can  reproduce  the  series  in  orders 
other  than  that  in  which  the  list  was  presented,  more  easily 
than  one  using  no  visual  imagery.  It  is  further  assumed  that 
the  nature  of  the  errors  made  will  reveal  the  character  of  the 
imagery.  If  confusions  are  made  where  the  appearance  of 
the  stimulus  letters  is  similar,  as  E  and  F,  while  the  sound  is 
different,  visual  imagery  is  assumed  to  have  been  used.  If 
the  confusions  are  of  letters  of  similar  sound,  such  as  Q  and 
U,  it  is  presumed  that  auditory  imagery  was  involved. 

This  method,  apart  from  the  many  complications  which 
have  been  introduced  into  it — in  my  own  work,  for  instance, 
where  it  has  been  combined  with  features  such  as  distrac¬ 
tions  and  helps  taken  from  other  tests — shares  with  the  ques¬ 
tionary  and  the  word  methods  the  advantages  of  stimulating 
introspection  in  a  very  useful  manner.  Like  the  word  method 
it  is  somewhat  superior  to  the  questionary  in  simulating  more 
nearly  a  normal  mental  task  and  its  results  are  accordingly 
more  likely  to  be  indicative  of  ordinary  imagery  processes. 

The  objective  features  of  the  test  are  quite  untrustworthy. 
For  instance,  persons  who  use  visual  imagery,  but  use  it 
poorly,  may  be  able  to  visualize  the  separate  letters  in  mem¬ 
ory,  but  be  quite  as  embarrassed  to  reproduce  them  in  an 
order  other  than  that  in  which  they  were  learned,  as  persons 

1  The  test  in  this  form  is  known  by  the  name  of  its  inventor,  Secor.  Anier.  Jour,  of 
Psych.,  1899,  vol.  xi,  p.  225.  The  literature  dealing  with  the  general  problems  of  asso¬ 
ciation  reactions  contains  much  available  material. 


70 


JAMES  R.  ANGELL. 


using  auditory  imagery.  Moreover,  persons  using  auditory- 
motor  imagery  are  by  no  means  unable  to  vary  the  order  in 
reproduction.  The  method  as  generally  used  affords  no  ade¬ 
quate  means  of  distinguishing  auditory  from  kinaesthetic 
ideational  material,  leave  alone  the  distinction  of  sensational 
from  ideational  kinaesthetic  elements.  Again,  the  confu¬ 
sions  made  are  frequently  ambiguous,  so  far  as  concerns  indi¬ 
cating  the  imagery  employed.  When  the  letter  B  is  con¬ 
fused  with  P,  and  M  with  N,  it  is  evident  that  either  audi¬ 
tory  or  visual  similarity  would  afford  an  adequate  clue.  On 
the  other  hand  the  confusions  are  often  extremely  suggestive.^ 
Owing  to  the  remarkable  facility  with  which  some  individ¬ 
uals  ‘shunt’  from  one  form  of  imagery  to  another,  or  use  two 
or  more  forms  conjointly  in  a  given  test,  as  will  presently 
be  further  explained,  and  especially  in  view  of  the  ease  with 
which  they  may  use  words  as  substitutes  for  objective  forms 
of  imagery,  it  is  impossible  to  infer  with  confidence  the  domin¬ 
ation  of  a  given  kind  of  imagery  merely  from  the  objective 
results  attained. 

A  case  peculiar  to  my  own  learning  processes  in  this  test 
may  illustrate  another  possible  ambiguity.  If  I  am  obliged 
to  repeat  the  words  before  they  are  completely  learned,  my 
recall  is  likely  to  be  dominated  by  visual  processes.  On  the 
other  hand  if  I  am  allowed  to  proceed  until  the  learning  is 
quite  perfect,  the  recall  is  likely  to  be  mainly  in  auditory- 
motor  terms,  and  the  more  perfectly  automatized  the  act 
becomes,  the  more  I  lose  the  visual  element.  Judged  at  one 
stage  of  the  process,  I  should  then  be  set  down  as  a  visual- 
izer;  judged  at  another  stage,  I  should  be  auditory-vocal- 
motor. 

D.  General  Tests  on  Memory  and  Sense-Discrimination. 
As  these  tests  just  mentioned  concern  primarily  visual  and 
auditory  imagery  with  a  subordinate  recognition  of  motor 
images,  it  may  be  remarked  in  passing  that  all  tests  on  mem¬ 
ory  can  be  employed  to  throw  light  on  imagery  analysis. 


1  On  the  general  subject  of  linguistic  lapses  as  it  bears  on  this  subject,  see,  Bawden 
Psy.  Rev.  Monog.,  1900,  vol.  hi,  No.  14. 


MENTAL  IMAGERY. 


71 


and  most  of  the  recent  memory  investigations  have  been 
characterized  by  detailed  description  of  the  imagery  discov¬ 
ered.  Nonsense  syllables,  numbers,  words,  letters,  colors, 
tones,  noises,  every  kind  of  material  has  been  studied  in  this 
way.^  The  differences  between  immediate  and  mediate 
recall,  between  mere  recognition  and  independent  recall, 
between  memory  and  imagination,  have  been  pointed  out 
for  many  cases.  Tests  on  sensory  discrimination  have  been 
similarly  employed.  Wolfe’s  tests  on  tonal  memory,  and 
Lehmann’s  tests  on  the  discrimination  of  grays,  may  serve 
to  illustrate  the  point. ^ 

The  comments  made  on  the  merits  and  defects  of  the 
immediately  preceding  test  apply  here  too,  and  need  not  be 
repeated. 

E.  Tests  Based  on  Description.  Tests  of  this  character 
have  been  used  for  various  purposes  and  are  clearly  applic¬ 
able  to  the  investigation  of  certain  phases  of  imagery.  The 
tests  can  be  complicated  indefinitely  especially  by  combin¬ 
ation  with  distraction  and  help  devices.  The  observer  is 
shown  an  object  or  a  picture,  preferably  one  in  colors,  for  a 
definite  period,  e.g.,  ten  or  fifteen  seconds,  and  then  at  once, 
or  at  a  later  time,  is  asked  to  describe  what  was  seen.  Intro¬ 
spections  are  then  asked  concerning  the  process  during  the 
original  stimulation  and  that  involved  in  recall.  The  test 
proves  in  practice  to  elicit  a  good  deal  of  non-verbal  imagery 
not  easily  stimulated  in  other  tests. 

To  illustrate:  a  series  of  words  memorized  by  vision,  may 
be  recalled  almost  wholly  through  vocal-kinaesthetic  imag¬ 
ery,  thus  leading  to  the  inference  that  a  subject  uses  no  visual 
memory  material.  The  same  person  if  given  a  picture  to 
observe  and  subsequently  describe,  may  find  abundant  vis- 


‘  Several  experimenters  have  commented  upon  their  observations  that  visualizers 
tend  to  learn  more  slowly  than  audiles.  The  experiments  carried  on  in  the  Chicago 
Laboratory  have  not  confirmed  this  generalization.  Several  of  the  quickest  learners 
have  been  visual,  and  no  general  results  have  been  reached  which  substantiate  this 
view. 

*  Wolfe,  Phil.  Studien,  1886,  vol.  iii,  p.  534.  Lehmann,  Phil.  Studien,  1889,  vol  v, 
p.  96. 


72 


JAMES  R.  ANGELL. 


ual  imagery  present.  It  will  often  be  found  extremely  illum¬ 
inating  to  allow  the  subject  to  see  the  object  again  after  he 
has  given  his  description.^  The  discrepancies  between  the 
stimulus  and  the  memory  imagery  are  often  most  suggestive 
as  to  the  influences  under  which  imagery  is  built  up  and  the 
second  inspection  is  remarkably  helpful  in  inciting  the  subject 
to  greater  accuracy. 

In  this  connection  an  interesting  confirmation  of  the 
extremely  subtle  shifts  in  imagery  resulting  from  slightly 
altered  conditions  has  been  observed  by  Dr.  M.  R.  Fernald. 
Observers  have  been  found  whose  imagery  alters  to  a  con¬ 
siderable  extent  when  they  know  before  the  experiment  that 
a  description  of  the  picture  or  object  is  to  be  asked  of  them, 
as  compared  with  their  procedure  when  they  are  ignorant 
that  such  a  request  is  to  be  made.  In  the  former  case  words 
are  more  likely  to  be  used  during  the  inspection  of  the  picture 
or  object  and  the  recall  may  be  largely  in  word  form,  whereas 
otherwise  the  whole  process — inspection  and  recall  alike — 
may  be  dominantly  visual  with  little  or  no  evidence  of  verbal 
material. 

Skillfully  conducted,  the  test  is  an  excellent  one  which 
can  be  made  to  simulate  with  practical  fidelity  the  condi¬ 
tions  of  common  mental  processes.  Its  limitations  are  sim¬ 
ply  those  incident  to  all  subjective  tests,  i.e.,  difficulties  in 
introspection  and  lack  of  generality  in  the  results.  The  imag¬ 
ery  employed  in  describing  one  set  of  visual  experiences,  for 
instance,  may  differ  in  many  particulars  from  that  used  In 
recalling  another  set. 

F.  Tests  on  Reading.  We  may  mention  next  tests  involv¬ 
ing  reading,  {a)  aloud  by  the  experimenter,  the  subject  lis¬ 
tening,  {b)  by  the  subject  either  silently  or  aloud  with  refer¬ 
ence  either  to  (i)  immediate  introspection  on  the  process  of 
apprehension,  or  (2)  also  and  primarily  with  regard  to  the 
mode  of  recall  and  its  accuracy,  whether  tested  at  once  or 
after  an  interval,  whether  for  verbatim  transcript,  or  for  the 
giving  of  the  general  meaning.  It  is  ordinarily  advised  that 

1  Except  in  vision  the  test  is  not  significantly  different  from  memory  tests  elsewhere 
discussed  and  we  therefore  mention  only  the  visual  case  at  this  point. 


MENTAL  IMAGERY 


73 


the  materials  for  the  purpose  should  cover  a  considerable 
range  of  intellectual  interest  and  should  include  both  prose 
and  verse. 

An  interesting  variant  on  the  test  which  has  often  been 
used  as  a  test  on  verbal  imagination,  and  as  a  test  on  gen¬ 
eral  intelligence,  consists  in  the  submitting  to  the  subject 
prepared  sentences  in  which  occasional  words  or  parts  of 
words,  or  even  whole  phrases  have  been  left  out,  and  the 
subject  is  called  upon  to  supply  relevant  material  for  the 
gaps.  Sometimes  nouns  and  verbs  are  given  and  the  subject 
must  make  a  sentence.  This  is  similar  to  the  old  word-build¬ 
ing  game  where  the  prize  goes  to  the  competitor  who  can 
make  the  most  words  out  of  combinations  of  the  letters  in 
the  stimulus  word. 

Obviously  the  same  limitation  belongs  to  the  tests  of  the 
immediately  preceding  paragraph  as  that  which  we  have 
already  pointed  out  in  connection  with  the  test  I  E,  namely, 
that  certain  subjects  can  perform  them  using  little  or  no  dis¬ 
cernible  imagery  and  that  with  many  persons  introspection 
is  extremely  difficult.  On  the  other  hand  for  persons  of  strong 
auditory-motor  verbal  tendency  the  tests  may  prove  very 
useful. 

This  general  group  of  tests  in  any  of  its  forms  is  essentially 
subjective,  so  far  as  concerns  its  contribution  to  the  analysis 
of  imagery;  but  many  secondary  objective  indications  are 
found  in  the  actual  procedure.  It  is  a  distinctly  useful  group 
for  practiced  introspectionists,  though  in  general  unduly 
difficult  for  untrained  persons.  Its  greatest  merit  is  that  it 
employs  common  and  fundamental  forms  of  mental  activity 
for  investigation.  When  successfully  controlled,  it  gives 
information  bearing  directly  on  actual  norms  of  mental  con¬ 
duct.  It  is  easily  complicated  by  distraction  and  help 
methods,  often  with  excellent  results  in  the  facilitation  of 
introspection. 

G.  Tests  on  Sensory  Similarity  in  Recall.  This  test  has 
been  devised  by  Dr.  M.  R.  Fernald  and,  so  far  as  I  remenlber, 
has  not  been  previously  used  for  this  purpose.  The  test  has 
various  forms.  In  one  form  the  subject  is  given  a  word, 


74 


JAMES  R.  AN  CELL. 


say  ‘tone,’  and  asked  to  write  all  the  words  he  can  which  rhyme 
with  it.  His  introspections  are  asked  and  especially  as  con¬ 
cerns  any  words  which  suggested  themselves  and  were 
rejected.  Again,  a  subject  is  asked  to  write  all  the  words  he 
can  recall  which  end  with  certain  letters,  say  ‘ine’  regardless 
of  the  pronunciation  of  the  word.  In  other  forms  of  the  test 
lists  are  prepared  either  with  or  without  a  letter-square 
frame,  in  which  words  pronounced  alike,  but  spelled  differ¬ 
ently  are  to  be  memorized.  In  other  lists  words  spelled  alike, 
but  pronounced  differently  are  dictated.  Here,  as  in  the  dis¬ 
traction  tests,  one  might  assume  that  persons  using  visual 
imagery  would  fare  best  in  writing  lists  of  words  ending  in 
the  same  letters,  and  those  with  auditory  imagery  would  do 
best  in  writing  lists  which  rhyme.  Again  one  might  antici¬ 
pate  that  audiles  would  be  more  confused  in  memorizing  the 
lists  containing  words  pronounced  alike  and  spelled  differ¬ 
ently,  whereas  the  visualizer  would  fare  worse  on  words  spelled 
alike  and  pronounced  differently.^  But  like  all  attempts  at 
objectively  valid  tests,  the  results  here  are  untrustworthy. 
Nevertheless,  the  ‘rhyming’  brought  out  auditory  or  vocal- 
motor  verbal  imagery  in  practically  every  case  examined,  and 
persons  who  use  such  materials  normally  found  it  present 
here  in  great  distinctness  and  profusion. 

If  persons  were  rigidly  confined  to  the  use  of  a  single  kind 
of  imagery,  objective  tests  of  this  variety  might  be  practi¬ 
cable.  In  point  of  fact,  however,  as  we  have  repeatedly 
noted,  individuals  are  rarely  or  never  so  circumscribed  as 
regards  their  available  imagery  that  they  cannot  at  need  fall 
back  upon  some  variety  not  regularly  used,  or  by  calling  in 
supplementary  aids  manage  to  master  the  situation.  For 
example,  an  individual  who  commonly  uses  visual  imagery 
for  purposes  of  recall  of  objects  may,  in  the  recall  of  words, 
spelled  alike  but  pronounced  differently,  resort  either  to  the 


^  Such  words  as  the  following  have  been  used:  cite,  site,  dew,  due,  scent,  cent,  sent; 
lead,  as  a  verb  and  as  a  noun,  dove  as  a  verb  and  as  a  noun;  similarly  the  words  wind, 
row,  tear,  wound,  and  the  following  words,  which  also  have  two  pronunciations,  close, 
bass,  live,  vase,  gill.  It  should  be  said  that  Dr.  Fernald  undertook  no  objective  appli¬ 
cation  of  the  test. 


MENTAL  IMAGERY. 


75 


use  of  auditory  and  kinaesthetic  imagery,  or  to  the  making  of 
supplementary  associations  of  a  helpful  kind  based  on  mean¬ 
ing.  The  objective  result  can  consequently  never  be  used 
apart  from  introspective  confirmation. 

As  a  stimulus  and  aid  to  introspection  the  tests  are 
extremely  useful ;  especially  as  regards  the  exhibition  of 
shunt  systems  in  imagery,  by  means  of  which  commonly 
unused  forms  or  devices  may  be  successfully  enlisted  when 
occasion  requires.  The  work  is  sufficiently  akin  to  normal 
mental  tasks  to  give  the  introspections  genuine  significance. 
Like  all  the  tests  thus  far  noticed,  with  the  possible  excep¬ 
tion  of  the  questionary,  disproportionate  emphasis  is  prob¬ 
ably  given  to  visual  and  auditory  materials  at  the  expense  of 
motor  imagery  other  than  the  linguistic  type,  whereas  the 
remaining  forms  of  imagery  are  practically  neglected  entirely. 

Dr.  Fernald  has  used  the  test  in  connection  with  letter- 
squares  employing  in  pairs  words  of  the  kind  described  and 
adding  distractions,  but  no  further  comment  need  be  made 
on  the  case. 

H.  Tests  Involving  Spelling.  These  can  be  used  in  a  num¬ 
ber  of  ways,  the  words  being  spelled  orally,  or  in  writing, 
with  eyes  shut  or  open,  spelling  forward  or  backward.  Tests 
on  backward  spelling  seem  to  have  been  used  less  than  one 
might  anticipate.  Like  the  previous  test,  this  type  may  be 
complicated  with  distraction  and  help  devices. 

It  is  an  admirable  form  of  test  to  use  in  conjunction  with 
tests  on  description,  in  as  much  as  it  brings  into  the  foreground 
peculiarities  of  verbal  imagery  as  compared  with  the  imagery 
of  objects.  This  virtue  constitutes  also  its  main  limitation. 
Other  forms  of  imagery  are  notably  infrequent  with  most 
subjects. 

I.  Tests  Involving  Simple  Problems.  Simple  arithmetical 
problems  may  illustrate  this  method.  The  addition  of  num¬ 
bers  seen  or  dictated,  the  multiplication  of  others,  serve  to 
give  material  for  introspection.  The  problems  can  of  course 
be  complicated  indefinitely  and  can  be  connected  with  prac¬ 
tical  situations  after  the  manner  of  the  text-books  on  arith¬ 
metic.  Geometry  and  Algebra  can  be  similarly  drawn  upon. 


76 


JAMES  R.  AN  CELL. 


Tests  on  geometrical  forms  are  peculiarly  successful  in  throw¬ 
ing  visual  imagery  into  the  foreground  and  algebraic  prob¬ 
lems  often  emphasize  motor  elements.  Mental  manipula¬ 
tions  of  the  cube  have  been  frequently  employed:  e.g.,  think 
of  a  cube;  cut  it  through  from  top  to  bottom  on  a  line  joining 
two  diagonally  opposite  corners;  what  shapes  have  the 
resulting  pieces?  Problems  in  ethics,  in  physics,  or  in  deport¬ 
ment,  anything  one  chooses  may  be  employed,  and  when  the 
conclusion  has  been  reached,  the  subject  is  asked  to  describe 
as  fully  as  possible  the  mental  material  used  in  reaching  a 
solution.  Or  he  may  be  unexpectedly  interrupted  during  the 
process  and  asked  to  report  his  introspection. 

For  persons  unpracticed  in  introspection  the  problems  must 
be  very  simple.  (The  ‘imageless  thought’  advocates  must  be 
reckoned  with  in  interpreting  the  results  of  any  such  tests). 
There  is  always  danger  that  the  imagery  recorded  may  not 
have  been  essential  to  the  solution,  but  rather  a  fringe  of 
more  or  less  irrelevant  suggestion.  If  this  danger  can  be  safe¬ 
guarded,  and  only  by  accurate  introspections  can  it  be,  the 
test  can  be  made  very  useful,  and  it  has  as  not  the  least  of  its 
merits,  the  normality  of  the  tasks  set. 

J.  Tests  with  Writing.  A  great  deal  of  experimentation 
on  the  processes  of  writing  is  more  or  less  directly  available 
for  purposes  of  analyzing  imagery.  When  so  applied,  the 
aim  is  of  course  to  devise  situations  in  which  the  imagery 
employed  may  be  thrown  into  the  foreground  of  conscious¬ 
ness  so  as  to  be  introspectively  available.  Writing  from  dic¬ 
tation,  from  printed  or  written  copy,  from  memory;  writing 
prose  or  poetry,  writing  not  only  forward  but  backward, 
and  also  upside  down,  left-handed,  and  in  looking-glass  script, 
writing  amid  various  distractions,  all  have  been  tried  and 
with  most  interesting  results.  These  tests  lead  naturally  to 
the  mention  of  a  large  group  of  tests  devised  primarily,  as 
were  the  foregoing,  for  the  study  of  voluntary  control. 

K.  General  Tests  on  Voluntary  Control.  Here  may  be  men¬ 
tioned  in  addition  to  the  tests  on  reading  and  writing,  tests 
on  the  use  of  habitual  coordinations  such  as  are  concerned  in 
speech,  in  walking,  in  grasping  objects,  in  muscular  reaction 


MENTAL  IMAGERY. 


77 


to  various  kinds  of  stimuli,  and  especially,  tests  on  the  secur¬ 
ing  of  control  over  new  coordinations.  The  latter  may  be 
illustrated  by  the  experiments  on  learning  to  move  the  ear, 
learning  to  move  the  final  joint  of  the  fingers,  independently 
of  the  lower  joints.  The  learning  of  acts  of  skill  such  as  type¬ 
writing,  skating,  bicycle  riding  and  the  like,  represent  another 
important  group. 

All  of  these  tests,  except  those  on  learning  to  control  new 
muscles,  enjoy  one  merit  in  common,  i.e.,  that  they  repre¬ 
sent  in  the  most  concrete  and  tangible  form  ordinary  kinds  of 
occupations  which  are  largely  free  of  the  merely  laboratory 
flavor.  They  all  suffer  too,  under  a  common  disability,  i.e., 
that  for  unpracticed  observers,  the  introspection  is  often 
extremely  difficult,  and  sometimes  essentially  impossible. 
Many  sensory  elements  are  inevitably  interwoven  with  the 
ideational  ones,  and  this  adds  a  very  distracting  complica¬ 
tion  which  destroys  confident  introspection  on  the  imagery 
for  not  a  few  observers,  even  of  the  practiced  sort. 

L.  Tests  for  Kinaesthetic  Imagery.  The  experiments  just 
referred  to  on  voluntary  control  frequently  bring  into  marked 
prominence  the  presence  of  motor  imagery  so-called,  and  most 
of  the  tests  previously  mentioned  serve  to  disclose  the  part 
played  in  mental  life  by  the  articulatory  imagery.  It  might 
seem  that  any  further  mention  of  motor  imagery  would  be 
superfluous.  (We  waive  here,  as  previously,  the  question 
whether  such  alleged  imagery  is  or  is  not  invariably  con¬ 
nected  with  muscular  excitation,  with  the  sensory  results  of 
which  it  is  merged.)  But  it  is  worthy  of  mention  that  in 
tests  specially  devoted  to  the  analysis  of  motor  memory  we 
sometimes  secure  clearer  evidence  of  this  type  of  imagery 
than  in  such  tests  as  we  have  heretofore  described,  in  which 
attention  is  in  the  nature  of  the  case  less  immediately  directed 
at  the  motor  act,  and  more  immediately  directed  at  the 
objective  results  of  the  act.  Tests  on  the  estimation  of  the 
extent  of  successive  arm-movements  may  illustrate  the  point. 
Many  subjects  to  be  sure,  make  judgments  of  this  kind  by 
means  of  secondary  criteria,  such  as  the  time  and  rate  of 
movement,  or  by  immediate  discriminative  reactions,  in 


78 


JAMES  R.  AN  CELL. 


which  no  kinaesthetic  imagery  appears.  But  others  resort 
very  definitely  to  the  kinaesthetic  image,  or  to  something 
which  they  regard  as  this  image,  and  compare  with  it  the 
second  reaction. 

Obviously  any  muscle  group  may  be  submitted  to  tests  of 
this  character,  and  any  exploration  of  motor  imagery  which  is 
to  be  complete  must  make  some  such  general  survey  before 
it  can  be  accepted. 

A  further  form  of  motor  test  which  has  been  studied  in 
the  Chicago  Laboratory  on  several  occasions  consists  in 
allowing  a  blind-folded  subject  to  trace  with  a  short  pencil 
patterns  of  various  designs  cut  out  of  wood  or  brass.  For 
one  form  of  test  he  traces  the  pattern  with  the  intent  to 
determine  its  shape,  which  he  is  then  asked  to  draw  on  a 
sheet  of  paper,  his  eyes  still  being  closed.  In  other  forms  he 
is  asked  to  find  and  draw  perfectly  the  true  pathway  of  a 
maze.  The  maze  may  then  be  rotated  through  45,°  90°  or 
270°  and  the  effects  noticed.  Or  the  patterns  may  be  traced 
over  the  head  or  with  the  hands  behind  the  back.  Intro¬ 
spections  are  required  in  every  case. 

These  tracery  tests  are  frequently  much  more  successful 
in  eliciting  visual  imagery  than  kinaesthetic,  but  with  cer¬ 
tain  persons  they  bring  out  the  kinaesthetic  element  with 
great  distinctness. 

Another  form  of  motor  imagery,  or  at  least  another  way 
of  using  it,  must  be  recognized  and  provided  for  in  any  ade¬ 
quate  tests  although  it  is  introspectively  very  difficult  to 
identify  and  only  practiced  observers  are  likely  to  detect  it. 
I  refer  to  what  Professor  Colvin,  in  a  recent  very  interesting 
papeP  has  termed  ‘mimetic  imagery,’  not  altogether  hap¬ 
pily,  as  it  seems  to  me,  for  although  the  imagery  is  sometimes 
mimetic,  and  possibly  it  was  all  originally  so,  it  is  often  purely 
symbolic.  I  should  prefer  the  term  ‘symbolic  motor  imag¬ 
ery.’  I  have  had  one  marked  case  under  observation  more  or 
less  directly  for  upwards  of  twenty  years.  The  matter  is 
referred  to  in  my  Psychology,  but  in  a  manner  which  might 
well  escape  attention. 


^  Psych.  Bull.,  \'ol.  vi.,  1910,  p.  223. 


MENTAL  IMAGERY. 


79 


Individuals  using  this  form  of  imagery  carry  on  their 
reflective  thinking  in  terms  of  schematic  and  often  faint  motor 
imagery  which  they  use  in  as  purely  symbolic  a  way  as  that 
in  which  verbal  thinkers  use  their  words. 

No  special  tests  have  been  devised  so  far  as  I  know  to 
bring  out  this  type  of  imagery,  and  I  have  none  to  suggest. 
If  the  subject  of  the  test  is  introspectively  acute,  almost  any 
of  the  tests  heretofore  described  will  serve  the  purpose,  par¬ 
ticularly  perhaps  those  dealing  with  the  solution  of  simple 
problems.  If  this  introspective  alertness  is  wanting,  I  know 
of  no  device  which  will  materially  assist.  None  of  the  ordin¬ 
ary  distraction  and  help  tests  promises  to  be  of  any  substan¬ 
tial  assistance,  because  the  imagery  employed  carries  a  sym¬ 
bolic  import  often  entirely  remote  from  any  peripheral  factor 
that  can  be  introduced.  It  is  accordingly  all  but  impossible 
to  impede  the  flow  of  the  imagery  except  by  such  distractions 
as  obliterate  the  attention  process  itself ;  and  aids  are  equally 
impracticable  because  one  cannot  anticipate  and  so  ‘hitch 
on  to’  the  reigning  symbolism. 

M.  Cutaneous  Imagery.  The  main  fields  for  the  collection 
of  evidence  dealing  with  this  group  of  images,  apart  from  the 
questionary,  have  been  the  tests  on  sensory  discrimination, 
as  in  the  experiments  on  touch  and  temperature,  those  on 
localization  and  a  few  on  memory.  They  seem  to  indicate  in 
general,  that  imagery  of  the  several  cutaneous  varieties  can 
be  detected  by  most  persons  under  favorable  conditions,  that 
with  not  a  few  individuals  it  is  very  vivid,  that  it  is  subject 
to  confusion  of  a  very  baffling  kind  with  the  corresponding 
sensations,  and  finally,  that  many  people  make  little  or  no 
use  of  it  if  other  imagery  can  function  for  it,  as  is  generally 
the  case,  particularly  where,  as  in  localization  processes,  vis¬ 
ual  images  are  available. 

N.  Organic  Imagery.  Introspection,  which  is  practically 
the  only  mode  of  approach  to  organic  images,  is  peculiarly 
difficult  for  two  reasons:  (i)  We  have  little  practical  neces¬ 
sity  to  attend  to  imagery  of  this  variety  and  we  may  well 
suppose  that  lack  of  practice  is  as  significant  here  as  it  is 
elsewhere.  (2)  Much  more  important,  however,  is  the  well 


8o 


JAMES  R.  AN  CELL. 


recognized  fact  that  when  we  attempt  to  call  up  an  organic 
image  we  are  likely  to  stimulate  reflexly  motor  and  circula¬ 
tory  changes  in  the  part  of  the  body  thought  of,  and  forth¬ 
with,  we  have  sensations  blending  with  or  displacing  our 
images.  So  much  is  this  the  case,  that  not  a  few  trustworthy 
psychologists  deny  the  reality  of  organic  images  just  as  they 
have  denied  the  existence  of  kinaesthetic  images. 

0.  Tests  071  Gustatory  and  Olfactory  Imagery.  Little  or 
nothing  has  been  successfully  achieved  here  to  work  out  a 
special  technique,  and  our  information  rests  again  mainly 
on  (i)  ordinary  introspection,  (2)  sensory  discrimination 
tests,  and  (3)  memory  tests.  The  practical  difficulties  are, 
if  possible,  even  more  serious  than  in  the  case  of  the  previous 
group.  In  the  gustatory  process,  introspection  is  handi¬ 
capped  because  the  thought  of  tastes  almost  inevitably  excites 
reflexly  the  glands  and  muscles  of  the  mouth,  so  that  sensa¬ 
tions  are  at  once  aroused  to  fuse  with  or  displace  the  image, 
assuming  that  the  image  is  really  available.  Similarly,  in 
smell,  there  are  reflex  excitations  of  the  inspiratory  muscles 
leading  to  illusory  sensations. 

The  most  trustworthy  experimental  work  on  the  memory 
of  these  sensations  indicates  what  theoretically,  and  on  the 
basis  of  introspection  has  generally  been  held,  i.e.,  that  very 
few  persons  can  readily  get  genuine  olfactory  images.  This 
fact  is  a  trifle  paradoxical  in  view  of  the  extreme  ease  with 
which  olfactory  illusions  can  be  produced,  a  circumstance 
which  would  apparently  indicate  a  high  degree  of  central 
olfactory  excitability.  Taste-imagery  is  perhaps  more  fre¬ 
quent,  but  the  images  are  probably  fusions  of  several  dis¬ 
tinct  properties  as  are  the  corresponding  sensations,  and  they 
rarely  occur  free  of  combination  with  the  sensory  activities 
for  the  reasons  indicated  above. 

Part  II.  Recommendations. 

After  this  brief  resume  of  available  methods  we  may  pro¬ 
ceed  to  present  certain  recommendations  for  those  who  pro¬ 
pose  to  use  imagery  tests.  But  first  it  must  be  made  clear 


MENTAL  IMAGERY. 


8i 


what  conditions  such  recommendations  are  designed  to  meet. 

There  are  several  distinct  aims  which  have  been  more  or 
less  well  differentiated  in  the  previous  investigations  of  imag¬ 
ery. 

Tests  have  been  sought  by  psychologists  which  might  be 
used  with  groups  of  persons  in  an  objective  way  and  espec¬ 
ially  has  this  been  true  of  the  search  for  methods  to  use  with 
children  in  the  schools.  Other  investigators  have  been 
mainly  interested  in  the  intensive  analysis  of  individuals  and 
especially  in  the  search  for  Types.’  They  have  sought  (i)  to 
determine  all  the  forms  of  imagery  which  an  individual  can 
command  at  will.  They  have  sought  (2)  to  ascertain  the 
forms  actually  employed  in  the  common  mental  processes 
of  daily  life.  This  latter  undertaking  may  be  so  executed  as 
to  determine  not  merely  what  imagery  is  thus  used,  but  also 
how  it  is  used  as  regards  the  distribution  of  the  several  varie¬ 
ties  of  it  among  different  kinds  of  mental  activities.  In  more 
.  detailed  execution  of  both  these  two  main  aims,  attempts 
have  generally  been  made  to  grade  the  imagery  discovered 
with  reference  to  one  or  more  of  its  ordinarily  recognized 
characteristics  like  intensity,  stability,  profusion,  accuracy, 
ease  of  attainment  and  the  like. 

Investigations  have  also  been  made  with  a  view  to  deter¬ 
mining  the  function  of  imagery.  In  this  connection  we  meet 
the  experimental  literature  of  imageless  thought. 

No  one  of  these  aims  can  be  realized  by  any  single  quickly 
executed  test  and  one  must  squarely  face  the  alternative  of 
abandoning  any  pretense  of  accurate  information  concern¬ 
ing  the  imagery  of  a  given  individual,  or  else  of  undertaking 
a  rather  extended  group  of  tests,  whose  outcome  may  be 
finally  problematic  if  the  subject  proves  too  deficient  in  intro¬ 
spective  powers. 

One  will  be  well  advised  who  enters  upon  such  analyses 
without  expecting  to  come  at  once  upon  any  of  the  conven¬ 
tionally  accepted  Types.’  Certainly  the  visual  and  auditory 
types  of  Charcot  and  Galton  will  rarely  be  recognized  in  any 
adequate  tests,  and  even  the  more  recent  distinction  of  word- 
types  and  object- types  will  be  found  extremely  elusive  in 


82 


JAMES  R.  ANGELL. 


many  cases.  The  shifting  and  substituting  of  one  form  of 
imagery  for  another  under  slight  changes  of  conditions,  where 
no  one  could  possibly  have  suspected  the  occurrence  of  such 
a  transformation,  speedily  render  the  unprejudiced  observer 
skeptical  of  all  rigid  divisions  into  types  of  the  familiar  kind. 
This  is  not  to  deny  the  reality  of  types,  but  simple  to  urge 
that  they  do  not  follow  with  any  great  regularity  the  lines 
heretofore  laid  down.  They  represent  problems  we  still  have 
to  solve,  rather  than  solid  foundations  on  which  we  can  build. 
A  subject  who  uses  visual-object  imagery  almost  wholly  in 
one  class  of  tests  may  be  equally  wedded  to  auditory-motor 
word  imagery  in  another  type.  My  own  observations  have 
abundantly  convinced  me  of  this,  and  confirmation  exists  in 
plenty  in  the  extant  literature  of  the  subject.  No  doubt  it 
often  occurs  that  imagery  of  some  one  sensory  mode  domin¬ 
ates  markedly  over  others,  but  the  predominance  is  probably 
in  many  cases  much  less  than  has  been  generally  assumed 
since  the  work  of  Charcot  and  Galton,  and  it  is  certainly 
much  more  difficult  to  establish  the  facts  than  has  been  com¬ 
monly  recognized. 

As  far  as  possible  it  seems  desirable  to  make  a  considerable 
number  of  the  tests  used  comparable  in  character  with  ordin¬ 
ary  mental  occupations,  so  that  the  results  may  have  a  closer 
bearing  on  normal  conditions.  This  may  be  urged  while  still 
recognizing  that  such  tests  need  to  be  supplemented  by 
others  designed  to  sound  possibilities  rather  than  merely  to 
determine  norms.  We  must  admit  the  possibility  that  even 
our  tests  intended  to  simulate  ordinary  tasks  and  familiar 
situations  may  be  abortive  simply  because  they  are  known  to 
be  experiments  on  which  introspection  will  subsequently  be 
demanded.  The  failure  of  all  purely  objective  tests  robs  us 
of  any  power  wholly  to  escape  this  possible  difficulty.  No 
doubt  this  element  enters  in  to  disturb  certain  results.  We 
have  mentioned  above  cases  where  the  knowledge  that  intro¬ 
spections  were  to  be  asked  has  radically  transformed  the  char¬ 
acter  of  the  imagery.  However,  it  has  not  been  because  the 
subjects  were  attempting  to  take  at  one  and  the  same  time 
two  contradictory  attitudes,  one  of  absorbed  learning  and  one 


MENTAL  IMAGERY. 


83 


of  watching  the  learning,  but  simply  because  the  attitude  of 
memorizing  with  the  expectation  of  being  subsequently 
tested  proves  to  be  different  from  the  attitude  of  concentrated 
attention  without  thought  of  future  recall.  The  difficulty 
must  be  recognized  and  as  far  as  possible  overcome.  It  is  in 
no  way  fatal  and  is  one  familiar  to  every  experimentalist. 

We  shall  recommend  two  groups  of  tests  containing  in 
part  identical  members.  One  of  these  will  be  designed  to 
furnish  a  brief  survey  of  the  imagery  capacities  of  the  subject 
and  the  other  will  offer  a  more  intensive  and  more  accurate 
analysis.  The  tests  selected  are  believed  to  possess  points  of 
superiority  in  each  case  justifying  their  selection  in  prefer¬ 
ence  to  other  available  ones. 

On  the  negative  side  it  is  to  be  clearly  understood  that  in 
this  report  we  are  not  primarily  engaged  upon  the  problem 
of  the  function  of  imagery.  It  is  also  to  be  understood  that 
the  defects  of  all  exclusively  objective  methods  debar  us  from 
recommending  any  series  of  tests  as  conspicuously  and  unam¬ 
biguously  suited  to  testing  groups  of  adults  or  children. 

For  the  briefer  series  we  recommend  as  described  below 
the  questionary,  the  test  on  melodies,  the  ‘description’  test, 
the  spelling  test,  the  reasoning  test  and  the  test  on  writing. 
This  provides  for  a  cursory  examination  at  least  of  voluntary 
imagination,  of  auditory  and  visual  objective  memory,  of 
auditory,  motor  and  visual  verbal  memory,  of  reasoning  and 
of  one  form  of  voluntary  control.  Save  for  the  questionary, 
such  a  group  of  tests  skillfully  conducted  need  not  occupy 
over  two  hours,  and  the  questionary  can  be  written  out  at 
leisure.  The  order  in  which  the  tests  is  given  is  not  essential, 
but  the  order  above  represented  is  advantageous  as  jt places 
the  reasoning  test  and  the  writing  test  last.  These  are  apt  to 
be  rather  more  difficult  than  the  others  to  secure  introspec¬ 
tions  from. 

The  recommended  tests  are  numbered  as  follows:  Part  II — 
l-A,  ll-D  (i),  ll-E,  ll-G,  lll-M,  IV-iV. 

For  the  more  extended  series  we  recommend,  in  the  form 
described  below,  the  questionary  as  a  test  on  voluntary 
imagination;  an  association  word  test  and  a  test  on  verbal 


84 


JAMES  R.  ANGELL. 


similarities  as  testing  both  spontaneous  and  voluntary  verbal 
imagery.  If  one  wishes  for  the  sake  of  completeness  to  exam¬ 
ine  spontaneous  imagery  of  objects,  this  can  best  be  done  by 
taking  care  to  include  in  the  questionary  used  a  series  of  inqui¬ 
ries  about  the  train  of  images  in  revery  and  when  falling  asleep. 
We  regard  this  as  unnecessary,  because  the  essential  facts 
are  almost  certain  to  appear  in  connection  with  other  tests  to 
be  mentioned,  especially  the  descriptive  tests. 

In  the  range  of  memory  we  recommend  for  the  survey  of 
auditory  Imagery  a  test  on  single  tones,  one  on  melody  and 
harmony,  and  a  test  on  noise.  The  tests  on  words  occur  In 
connection  with  a  later  group.  For  the  analysis  primarily 
of  visual  memories  the  test  on  the  description  of  objects  and 
the  description  of  pictures,  colored  and  in  black  and  white, 
are  recommended.  These  will  care  for  objective-visual  imag¬ 
ery.  The  letter-square  test  and  the  spelling  will  bring  out 
the  verbal  material  and  the  first  may  be  used  for  forms 
and  numerals  also.  The  test  on  reading  should  be  added. 
It  belongs  in  part  to  the  analysis  of  perception,  in  part  to 
volition  and  in  part  to  memory.  It  sometimes  produces 
little  or  no  material  other  than  verbal ;  sometimes  it  succeeds 
in  calling  forth  profuse  objective  imagery.  In  any  case  it 
represents  a  highly  important  and  familiar  mental  operation 
which  should  not  be  omitted  from  examination.^ 

Kinaesthetic  memory  imagery  (?)  is  certain  to  be  elicited 
from  many  subjects  by  the  tests  on  melody,  on  words  and  on 
the  specific  voluntary  acts  like  writing.  It  can  be  further 
examined  in  the  tests  on  estimating  extent  of  movement,  and 
on  following  tracery  patterns. 

Cutaneous  memory  imagery  may  be  tested  by  experiments 
on  localization. 

No  special  tests  on  taste  are  recommended,  because  the 
results  of  all  those  available  are  too  ambiguous.  The  ques¬ 
tionary  replies  represent  about  as  high  an  order  of  accuracy 
as  we  can  secure  at  this  point. 

A  single  test  on  olfactory  memory  is  recommended  more 
by  way  of  completeness  than  because  its  outcome  is  likely 


MENTAL  IMAGERY. 


85 


to  be  very  important.  This  is  in  substance  Miss  Gamble’s 
test  on  reconstruction. 

On  reasoning  processes  we  recommend  problems  in  arith¬ 
metic  and  geometry  as  described  and  at  least  one  problem  of 
a  social  or  ethical  character,  and  one  of  a  purely  practical 
character. 

Tests  on  voluntary  control  may  be  carried  out  to  great 
advantage  in  any  learning  process  and  an  extensive  literature 
is  at  hand  for  guidance  in  such  tests.  We  recommend  only 
the  tests  on  writing,  (i)  because  the  consumption  of  time  in 
the  other  tests  is  prohibitive  for  most  persons  and  (2)  because, 
with  the  exception  of  the  cases  where  a  new  and  unused  mus¬ 
cle  group  is  coming  under  control,  we  believe  the  writing  con¬ 
trol  is  essentially  typical  of  all  the  ordinary  motor  activities 
under  conscious  direction. 

Such  a  group  of  tests  as  this  intelligently  applied,  with 
the  minor  variations  which  may  be  required  by  the  peculiar¬ 
ities  of  a  given  subject,  will  result  not  only  in  affording  a 
highly  satisfactory  inventory  of  the  individual’s  equipment  of 
imagery,  it  will  also  convey  a  very  significant  impression  of 
the  actual  distribution  of  his  imagery  and  of  the  manner  in 
which  he  uses  it. 

We  pass  now  to  a  more  explicit  and  detailed  account  of 
the  tests  selected,  together  with  a  brief  commentary  upon 
their  characteristics. 

In  order  to  make  sure  that  the  tests  chosen  cover  the  ground 
fairly  each  of  the  main  forms  of  mental  activity  involving 
imagery  is  herewith  examined.  For  practical  purposes  this 
may  be  done  by  examining  the  play  of  imagination  under 
various  conditions,  (this  includes  the  process  of  apprehending 
meaning  as  in  listening  to  reading  or  talking) ;  the  use  of  mem¬ 
ory,  both  mediate  and  immediate;  the  process  of  reasoning 
and  the  execution  of  acts  of  voluntary  control.  The  tests 
recommended  are  grouped  on  this  basis,  although  other  princi¬ 
ples  of  classification  might  be  equally  useful.  Apology  may  be 
made  once  and  for  all  for  the  inevitable  repetition  in  the  next 
section  of  points  touched  on  in  the  first  part  of  this  report. 


86 


JAMES  R.  AN  CELL. 


DIVISION  I. 

Imagination. 

A.  Questionary.  Although  as  commonly  employed,  the 
questionary  involves  a  measure  of  distinctively  memory 
material,  as  a  whole  the  method  may  be  regarded  as  one 
appealing  primarily  to  the  voluntary  use  of  imagination.  It 
is,  moreover,  the  best  available  general  test  on  this  mental 
process  and  may  with  rare  exceptions  be  advantageously  used.^ 

Several  questionaries  are  available  of  which  Galton’s, 
Titchener’s,  Seashore’s  and  Betts’  may  be  mentioned. ^ 
These  may  serve  as  patterns.  The  last  three  possess  advan¬ 
tages  over  Galton’s,  but  his  has  been  so  frequently  used  that 
there  is  a  good  deal  of  interest  in  comparing  one’s  results 
gained  by  means  of  it  with  those  previously  reported.  The 
main  considerations  to  be  met  by  such  a  document  are  clar¬ 
ity  of  questions,  recognition  of  every  genus  of  images  and  each 
important  species,  and  care  not  to  over-emphasize  the  com¬ 
moner  varieties  such  as  visual  and  auditory;  suggestions  for 
evaluating  on  some  arbitrary  scale  differences  in  such  char¬ 
acteristics  as  vividness,  accuracy,  detail,  permanency,  and 
ease  of  control  of  the  various  images.  The  length  of  the 
document  and  the  refinement  of  questions  into  which  it  goes 
are  matters  to  be  decided  by  the  amount  of  time  available. 

B.  Association  Test.  Certain  of  the  tests  on  association 
are  fairly  to  be  regarded  as  tests  of  imagination  and  one  of 
these  we  recommend  because  of  its  simplicity  and  ease  of 
application  and  also  because,  as  contrasted  with  the  ques¬ 
tionary,  it  brings  out  spontaneous  in  distinction  from  volun¬ 
tary  imagery.  It  Involves  on  the  whole  a  more  natural  type 
of  mental  act  than  the  questionary.  With  some  subjects 
the  test  is  likely  to  prove  merely  a  test  of  verbal  imagination, 
but  even  so  it  is  worth  making. 

Two  lists  of  words  should  be  prepared,  the  number  to  be 

^  It  will  be  remembered  perhaps  that  we  have  rejected  such  tests  as  the  ink-blot 
test,  which  undoubtedly  have  an  interesting  bearing  on  certain  forms  of  constructive 
capacity,  because  they  do  not  bring  out  imagery  with  sufficient  certainty. 

^  Galton,  Inquiries  into  Htiman  Faculty,  Appendix  E;  Titchener,  Experimental 
Psychology;  Student’s  Manual,  Qualitative,  198;  Seashore,  Elementary  Experiments  in 
Psychology,  108;  Betts,  Distribution  and  Function  of  Mental  Imagery,  p.  20. 


MENTAL  IMAGERY. 


87 


determined  by  the  time  available  (twenty  has  proved  a  con¬ 
venient  number  in  my  own  tests  and  those  of  others),  but  not 
less  in  number  than  will  allow  some  appeal  to  each  important 
type  of  imagery.!  One  of  these  lists  is  to  be  read  visually,  a 
word  at  a  time,  by  the  subject,  the  other  is  to  be  read  to  him 
orally.  After  each  word  he  is  to  write  down  the  idea  or 
word  suggested  by  the  stimulus  word,  describing  the  imagery 
in  which  the  associates  are  presented. 

Sometimes  the  test  is  made  by  confining  the  reaction  to 
this  associated  idea,  sometimes  the  associative  train  is  allowed 
to  run  on  for  a  period — five  or  ten  seconds  or  more.  The 
series  is  at  once  recorded  and  introspections  are  given.  Other 
complications  such  as  distraction  can  be  introduced.  With 
unpracticed  subjects  the  briefer  procedure  is  preferable. 
With  practiced  introspectionists  the  results  of  the  longer 
trains  are  more  suggestive,  although  difficult  to  tabulate  or 
quantify  satisfactorily. 

C.  Sensory  Similarity.  We  recommend  a  test  which  lies 
on  the  border  between  imagination  and  memory  involving 
in  part  spontaneous  and  in  part  voluntary  reactions.  This 
is  the  test  on  sensory  similarity.  The  subject  is  given 
a  word  e.g.,  ‘cat’  and  told  to  write  all  the  words  he  can  which 
rhyme  with  it .  He  is  then  instructed  to  write  all  the  words 
he  can  think  of  ending  in  a  given  series  of  letters,  e.g.,  ‘ous’ 
without  regard  to  their  pronunciation.  A  limited  time,  five 
minutes  perhaps,  is  set,  and  introspections  are  asked.  Several 
experiments  may  profitably  be  made  with  different  word- 
stimuli.  The  test  is  even  more  purely  verbal  than  the  previous 
one,  but  in  practice  the  rhyming  form  has  been  found  to  be 
peculiarly  useful  in  throwing  into  the  foreground  of  con¬ 
sciousness  auditory  and  motor  speech  imagery,  not  so 
readily  observed  in  the  preceding  tests.  The  other  form 
appeals  strongly  to  visual  imagery.  Like  all  these  tests  it  can 
be  complicated  indefinitely  by  distractions  and  other  devices. 

^  The  experiences  in  the  Chicago  Laboratory  would  not  indicate  that  any  particular 
words  chosen  possessed  permanent  merit  over  others.  The  list  published  bySecor 
{Amer.  Journ.  of  Psych.,  vol.  xi,  p.  225  ff.)  may  serve  as  an  example,  although  it  tends 
to  slight  possible  taste  and  smell  imagery.  Such  words  as  sky,  whistle,  violets,  sugar, 
ice  may  illustrate  the  materials. 


88 


JAMES  R.  AN  CELL. 


DIVISION  II. 

Memory. 

To  be  in  any  way  complete  as  an  account  of  the  use  made  of 
imagery  in  memory  processes,  involves  tests  covering  the  various 
sense  departments  recognizing  the  difference  between  mediate 
and  immediate  memory,  and  the  differences  dependent  on 
the  condition  during  learning,  e.g.,  whether  the  subject  knows 
he  is  to  be  examined  on  his  knowledge.  The  tests  will  be 
described  without  invariable  reference  to  these  qualifications, 
but  it  must  be  clearly  understood  that  they  concern  factors 
which  distinctly  affect  imagery.  They  must  be  taken  into 
account  in  any  complete  series  of  tests. 

D.  Auditory  Tests, — Tone.  Two  types  of  tests  on  tone 
imagery  are  available,  one  involving  single  tones,  or  groups 
of  tones  experienced  simultaneously,  the  other  involving 
melody,  thus  bringing  in  rhythm  and  if  desired,  harmony. 
The  second  can  be  complicated  indefinitely  by  adding  har¬ 
monization  in  terms  of  a  single  instrument  like  the  piano,  or 
of  many  instruments  as  in  an  orchestra.  The  phonograph 
can  be  used  for  this  purpose.  With  persons  richly  endowed 
with  auditory  imagery  the  m^ore  complex  tests  are  sure  to 
be  worth  while  in  disclosing  intricacies  in  the  organization  of 
imagery  not  otherwise  revealed. 

(i)  The  test  can  be  made  with  any  musical  instruments 
but  a  familiar  instrument  like  the  piano  is  preferable,  as 
strangeness  of  tone  quality  is  a  distraction  to  untrained  ob¬ 
servers,  and  even  with  trained  observers,  the  familiar  tones 
are  more  easily  and  confidently  reproduced.  If  brevity  of 
time  must  be  consulted,  the  test  on  single  tones  may  better 
be  omitted  than  that  on  melody.  The  writer  has  never 
chanced  to  find  a  case  where  auditory  imagery  was  gotten 
with  one  test  and  not  with  the  other;  but  the  relative  vividness 
of  the  imagery  occasioned  by  the  two  tests  varies  with  dif¬ 
ferent  individuals,  so  that  on  a  scale  to  show  this  feature  the 
tests  would  give  contradictory  results.  The  melody  test 
simulates  common  experience  more  closely  than  the  other 
and  is  easier  for  untrained  subjects  to  perform. 


MENTAL  IMAGERY. 


89 


The  subject  is  told  that  the  first  few  notes  of  a  familiar 
melody  will  be  played,  enough  so  that  he  can  recognize  it. 
He  is  then  to  finish  the  melody  mentally — fin  his  head.’ 
Then  he  is  asked  to  describe  the  experience.  Tone  quality, 
pitch  and  tempo  should  be  noted  and  the  melody  may  then  be 
actually  played  through  again  to  see  how  it  compares  with 
the  subject’s  recollection  of  it.  If  possible,  the  melodies 
should  be  played  at  three  points  on  the  tone  scale,  namely 
in  the  deep  bass,  in  the  high  treble  and  in  the  middle  register. 

The  test  has  two  disadvantages,  (i)  with  persons  possess¬ 
ing  weak  auditory,  but  strong  vocal  kinaesthetic  imagery,  it 
tends  to  the  submerging  of  the  auditory  in  the  kinaesthetic. 
(2)  If  the  melody  has  familiar  words  set  to  it,  persons  of 
strong  verbal  imagery  may  again  tend  to  swamp  the  auditory 
factors  with  enunciatory  elements.  The  chief  merit  of  the 
test  is  that  it  'works  itself’  almost  without  instructions,  pro¬ 
vided  the  subject  has  any  musical  imagery  at  all. 

(2)  The  test  of  single  tones  is  conducted  as  follows;  A 
series  of  at  least  five  tones  is  chosen  forming  a  chromatic 
series,  no  successive  notes  to  be  more  than  a  half  tone  apart. 
The  piano  is  again  the  best  instrument,  but  the  tuning  fork 
or  organ  pipes  of  the  ordinary  laboratory  equipment  will 
serve. 

A  tone  is  struck  by  the  experimenter,  the  subject  then 
counts  silently  'by  threes’  for  five  seconds  (to  break  up  the 
carrying  over  of  the  after-sensations,  or  the  suppressed  hum¬ 
ming  of  the  tone).  Then  he  is  asked  if  he  can  hear  the  tone 
mentally.  If  he  replies  'yes,’  the  operator  strikes  one  of  the 
closely  related  tones  and  asks,  'Is  it  this;’  striking  several 
notes,  one  after  the  other,  including  the  original  tone.  This 
procedure  not  only  stimulates  a  subject  to  try  to  form  a 
correct  image,  but  it  also  assists  him  to  observe  peculiarities 
in  the  image,  whether  it  is  relatively  faint  or  vivid,  whether 
it  is  flat  or  sharp  as  compared  with  the  original,  whether  the 
timbre  is  correct,  or  is,  as  often  happens,  the  tone  quality  of 
the  subject’s  own  voice. 

(3)  Noise.  Tests  on  the  auditory  imagery  for  noise 
have  less  practical  importance  and  for  diagnostic  purposes 


90 


JAMES  R.  ANGELL. 


are  only  essential  provided  the  questionary  has  given  nega¬ 
tive  results,  although  if  one  desires  to  ascertain  with  some 
approach  to  completeness  the  distribution  of  imagery  forms, 
such  a  test  as  follows  would  be  needed. 

A  test  may  be  made  following  the  lines  of  that  on  tones. 
Homely  devices  may  be  pressed  into  service.  A  large  empty 
box,  a  small  cigar  box,  a  table  top,  a  chair  back,  and  a  wooden 
rod,  may  serve  as  equipment.  Other  similar  utensils  will 
suggest  themselves.  The  first  four  articles  are  to  be  smartly 
struck  one  at  a  time  with  the  rod;  the  subject  is  to  count 
again  as  in  the  tone  test  and  then  try  whether  he  can  get 
an  image  of  the  noise.  The  experimenter  may  also  crush  in 
his  hand  a  stiff  piece  of  paper  using  a  single  quick  motion 
for  the  purpose.  He  may  also  make  a  sharp  hissing  sound 
and  test  the  subject’s  imagery  as  above  for  the  two  kinds  of 
stimuli. 

(4)  Numerals  and  Words.  Special  tests  on  the  memory  of 
numerals  and  words  from  auditory  stimulation  are  not  indis¬ 
pensable  in  view  of  the  tests  to  follow,  provided  one  is  seeking 
simply  for  the  existence  of  imagery  rather  than  its  distribu¬ 
tion.  But  if  for  any  reason  one  feels  the  need  of  tests  iso¬ 
lating  these  factors  more  completely,  the  following  is  recom¬ 
mended  : 

The  old  dictation  test  used  so  often  for  investigating  the 
memory  span.  Lists  of  digits  are  prepared  and  read  dis¬ 
tinctly  to  the  subject  in  groups  of  five,  six,  seven  or  more  at 
a  time,  thus— 7,  4,  3,  6,  9,  8,-5,  2,  7,  4,  9,  i,  3.  The  subject 
is  at  once  to  write  down  or  pronounce  the  numbers  as  remem¬ 
bered.  The  writing  is  likely  to  emphasize  visual  imagery  in 
persons  who  can  use  it  freely,  especially  if  done  with  closed 
eyes.  The  pronouncing  is  likely  to  emphasize  the  auditory 
vocal  elements.  The  lists  may  be  read  partly  without  rhythm, 
and  partly  with  it.  The  recall  will  generally  reflect  the 
effects  of  this  variation.  An  interruption  of  a  few  seconds 
between  the  stimulus  and  the  reproduction,  as  in  the  test  on 
tone,  will  naturally  decrease  accuracy  of  memory,  but  it  is 
quite  likely  to  assist  the  introspective  identification  of  the 
imagery. 


MENTAL  IMAGERY. 


91 


Nonsense  syllables  and  lists  of  disconnected  words  may  be 
similarly  dictated.  Mediate  memory  for  such  materials  may 
obviously  be  tested  by  learning  the  lists  by  heart  and  repro¬ 
ducing  after  an  interval  of  time. 

E.  Visual  Description  Tests.  Of  the  visual  tests  we 
recommend  the  following  which  in  practice  elicit  many  forms 
of  imagery  other  than  visual,  but  which  are  particularly 
successful  in  stimulating  the  latter.  They  belong  to  the 
general  class  of  description  tests. 

A  test  for  objective  visual  memory  may  profitably  be  used 
which  is  based  on  an  old  game.  In  a  tray  oron  a  table  are  placed 
at  least  ten  or  fifteen  small  and  familiar  objects — coin,  thimble 
penknife,  ring,  and  the  like.  Some  of  these  should  be  dis¬ 
tinctly  colored,  e.g.,  a  red  pen-wiper,  a  blue  ribbon  and  a 
yellow  pencil.  The  subject  is  allowed  to  inspect  the  articles 
for  a  specified  time — about  one  second  of  time  for  each 
article  has  been  found  judicious — and  he  is  thereupon  required 
to  write  down  or  name  all  the  articles  he  can  remember. 
His  introspections  are  then  taken,  and  questions  are  asked 
about  the  color,  size  and  relative  location  of  the  objects. 
An  excellent  test  proceeding  in  a  similar  manner  and  resem¬ 
bling  the  well-known  'Aussage’  tests,  involves  the  use  of  draw¬ 
ings,  part  of  which  should  be  colored  and  part  in  black  and 
white. ^  A  set  of  ten,  five  of  each,  will  serve  the  purpose. 
These  may  be  used  either  as  a  test  for  immediate  recall  or 
for  recall  after  a  few  minutes,  hours  or  days.^  In  either  case 
the  subject  is  asked  to  describe  the  picture  with  detail,  as  in 
the  preceding  tests  and  then  tell  how  he  executes  the  task, 
grading  his  imagery  if  intensive  classification  is  at  stake. 

1  Dr.  Fernald  has  used  successfully  prints  of  the  picture  postal  card  size.  She  has 
found  the  small  size  which  enables  the  eye  easily  to  get  the  whole  scene  at  a  glance 
preferable  to  larger  pictures  where  attention  is  scattered  more  widely  over  the  field. 

2  Although  the  imagery  changes  in  the  most  amazing  fashion  as  is  well  known,  the 
author  has  found  no  reason  to  think  that  commonly  there  is  a  change  in  memory 
depending  primarily  on  time,  from  one  sense  quality  such  as  vision  to  another  such  as 
audition.  One  may,  under  pressure  of  experimental  direction,  use  in  immediate  mem¬ 
ory  a  form  of  imagery  not  ordinarily  employed,  e.g.,  tactual;  but  if  the  immediate 
recall  would  normally  be  in  visual  terms,  the  recall  at  a  later  period  is  not  likely  to  be 
other  than  visual.  Other  investigators  have  confirmed  this.  Cf.  Segal,  Arch.f.  d.  ges. 
Psychol.  1908,  vol.,  xii,  p.  124. 


92 


JAMES  R.  AN  CELL. 


Questions  containing  erroneous  suggestions  as  to  what  he 
has  seen  bring  out  most  interesting  results  and  should  be 
followed  by  showing  the  picture  a  second  time. 

Where  the  test  is  used  merely  to  ascertain  the  presence  of 
imagery,  no  further  precautions  are  necessary,  and  it  may 
be  safely  laid  down  that  persons  who  secure  no  visual  imagery 
from  such  a  test  are,  practically  speaking,  lacking  in  it  alto¬ 
gether.  If  the  tests  are  used  as  a  method  of  ascertaining 
the  distribution  of  imagery  in  normal  processes,  a  sharp  dis¬ 
tinction  must  be  drawn  between  the  cases  in  which  the  subjects 
know  that  they  are  to  be  held  for  a  report  and  those  in  which 
they  are  unaware  of  this.  A  relatively  naif  inspection  of 
the  card  has  been  attained  by  Dr.  Fernald  through  the 
use  of  ‘puzzle  pictures,’  which  the  subject  inspects  merely 
to  find  the  concealed  objects.  This  gains  a  good  degree  of 
attention  without  throwing  the  subject  into  the  learning  at¬ 
titude.  But  the  same  result  can  be  gained  in  many  other 
ways.  The  pictures  may,  for  instance  be  shown  with  a  view 
to  passing  on  their  relative  aesthetic  excellence. 

F.  Letter  Square  Test.  Blanks  are  prepared  with  nine 
squares  arranged  to  form  a  larger  square.  (My  own  have  been 
I  inch  on  the  side,  making  a  large  square  3  inches  on  a  side.) 
In  these  squares  can  be  placed  numbers,  pictures,  forms, 
letters,  syllables,  or  words.  The  subject  reads  through  the 
list  three  times  and  then  attempts  to  reproduce  it  by  writing 
in  the  spaces  of  a  blank  form,  or  he  may  reproduce  the 
materials  verbally.  Introspections  are  then  asked.  The 
test  may  be  usefully  and  easily  complicated  in  several  ways; 
by  reading  (when  the  material  permits)  the  lists  aloud  to 
the  subject  after  which  he  is  to  put  the  remembered  elements 
in  appropriate  order  on  a  blank  square.  Distractions, 
auditory,  vocal-motor,  or  visual,  may  be  introduced  as  hereto¬ 
fore  described.  Rhythm  may  be  introduced,  the  subject 
may  be  instructed  to  think  of  the  material  in  groups  and  so 
on. 

This  test  is  one  of  the  best  in  the  list  for  bringing  out  verbal 
imagery,  both  visual  and  auditory-motor.  It  also  brings  out 
certain  forms  of  the  objective-visual,  but  it  is  on  the  whole 


MENTAL  IMAGERY. 


93 


much  less  satisfactory  for  producing  objective  imagery  than 
the  description  tests.  If  the  auditory  dictation  is  employed, 
it  would  rarely  be  worth  while  to  use  the  previous  test  on 
numerals  and  words,  number  II-D4.  Both  overlap  in  some 
degree  the  following  test  on  spelling,  a  test  which  ought  in 
no  event  to  be  omitted. 

G.  Spelling  Tests.  In  part  of  the  tests  the  subject  should 
write  the  word  to  be  spelled,  in  part  pronounce  the  letters. 
In  spelling  forward,  words  should  be  selected  which  will  put 
some  tax  on  the  subject’s  capacity — shorter  and  more  familiar 
words  can  be  used  with  children,  longer  and  more  uncommon 
words  being  selected  for  adults.  With  the  common  and  well 
known  words  the  spelling  will  often  be  found  so  highly  auto¬ 
matized  as  to  involve  little  or  no  imagery. 

Spelling  backwards  is  even  more  useful  than  spelling  for¬ 
ward.  The  test  can  be  made  in  two  ways:  (i)  The  subject 
is  given  a  word,  e.g.,  ‘locality,’  and  then  pronounces  or  writes — 
better  the  first — the  letters  of  the  word  backward.  (2)  The 
experimenter  pronounces  the  letters  backward  and  the  sub¬ 
ject  attempts  to  determine  the  word  and  pronounce  it  him¬ 
self.  The  control  of  the  rate  at  which  the  letters  are  read 
will  materially  effect  the  success  of  this  form  of  the  test. 
Different  subjects  vary  widely  in  their  response  to  the  test 
and  the  rate  must  be  adjusted  to  their  Individual  capacity. 
It  should  be  rapid  enough  to  keep  the  attention  strained,  but 
not  so  rapid  as  to  produce  a  serious  confusion.  For  most  sub¬ 
jects  the  rate  of  one  letter  per  second  is  a  good  one  to  begin 
with.  The  subject  gives  his  introspection  at  the  end  of  each 
test.  The  test  can  be  complicated  with  the  methods  of  dis¬ 
turbance  and  help. 

H.  Reading  Tests.  Reading  affords  an  opportunity  for 
various  forms  of  tests.  They  should  be  included  in  any 
series  designed  to  afford  a  survey  of  the  imagery  In  normal 
types  of  mental  action;  but  they  present  introspective  diffi¬ 
culties  which  often  render  them  of  secondary  value  for  use 
with  untrained  observers  and  especially  children. 

The  passages  selected  may  be  determined  in  part  by  local 
conditions.  As  a  rule  they  should  not  exceed  ten  or  fifteen 


94 


JAMES  R.  ANGELL. 


lines  in  length  and  may  well  be  shorter.  Both  prose  and 
poetry  should  be  represented,  and  among  the  poems  should 
be  representatives  of  well-known  songs  (to  stimulate  audi¬ 
tory-vocal  imagery).  They  may  advantageously  include 
(i)  passages  descriptive  of  nature  in  her  appeals  to  the  various 
senses,  (2)  passages  describing  some  concrete  practical  opera¬ 
tion,  e.g.,  the  planting  of  trees,  the  making  of  brick,  and  the 
like,  (3)  passages  discussing  some  distinctly  abstract  ideas, 
whether  of  a  philosophical  or  a  scientific  character. 

The  material  should  be  presented  (i)  visually  and  (2) 
orally.  It  should  be  given  (a)  under  conditions  where  the 
subject  knows  that  he  will  not  be  examined  on  the  contents 
of  the  passages.  He  is  simply  asked  to  read  or  listen  as  he 
would  in  the  case  of  any  matter  momentarily  attracting  his 
interest:  (b)  contrasted  with  this  procedure,  the  test  should 
be  made  when  the  subject  knows  he  is  to  be  asked  to  give 
the  import  of  the  passage.  This  he  may  either  write  or  give 
orally,  the  former  generally  proving  in  practice  the  more 
useful.  He  may  be  asked  for  the  general  import  of  the 
passages  or  for  as  much  as  he  can  recall  verbatim.  He  may 
react  at  once  or  after  an  interval  of  time.  His  introspections 
are  asked  both  on  the  process  of  apprehension  and  of  repro¬ 
duction.  The  passages  read  for  introspection  on  the  process 
of  apprehension  are  not  to  be  used  in  the  tests  on  retention. 
Various  complications  will  suggest  themselves. 

I.  Cutaneous  Tests.  For  contact  stimulations  the  sub¬ 
ject  (his  eyes  being  closed  or  averted)  may  be  touched  lightly 
on  the  forearm  with  a  blunt  cork  point.  He  then  counts 
aloud  by  ‘threes,’  for  ten  seconds,  to  allow  any  after-sensa¬ 
tions  to  subside.  He  then  attempts  to  recall  the  sensation 
and  points  at  the  spot  stimulated.  His  introspections  are 
then  requested. 

With  blunt  metal  rods  a  similar  test  may  be  made  for 
warmth  and  cold,  the  rods  being  kept  in  hot  or  cold  water 
and  carefully  wiped  before  being  applied  to  the  skin.  The 
points  should  feel  to  the  subject’s  skin  distinctly  cool  and 
distinctly  warm,  but  not  smarting  nor  painful  when  left  on 
a  few  seconds.  The  after-sensation  must  be  carefully  avoided. 


MENTAL  IMAGERY. 


95 


The  stimulations  should  in  no  case  exceed  a  second  in  dura¬ 
tion.  The  counting  should  go  on  for  at  least  ten  seconds, 
and  twenty  is  better.  The  subject  is  then  invited  to  recall 
the  sensation  if  possible  and  point  to  the  spot  where  it  was 
located. 

Pain  may  be  tested  by  a  light  needle  prick  or  by  snapping 
a  rubber  band  on  the  back  of  the  hand.  A  considerable 
interval  of  distraction  must  be  used,  the  length  depending 
on  the  violence  of  the  stimulus.  The  experimenter  must 
determine  himself  by  control  tests  how  long  to  allow  for  the 
subsidence  of  the  after-sensation.  Otherwise  the  procedure 
is  as  with  temperature  sensations. 

These  tests  fall  out  very  differently  with  different  persons, 
some  subjects  failing  to  get  the  images  with  any  certainty, 
others  getting  them  easily,  and  still  others  being  flooded  with 
visual  imagery  of  the  parts  stimulated.  But  it  may  be  fairly 
assumed  that  a  subject  who  under  these  conditions  gets  no 
trace  of  cutaneous  imagery,  never  makes  any  important  use 
of  it. 

Interesting  experiments  involving  imagery  from  fusions 
of  touch  and  motor  elements  may  be  made  by  using  the  raised 
letters  of  the  alphabet  for  the  blind.  The  subject  is  aside 
from  our  present  main  purpose  and  need  not  be  discussed. 

J.  Kinaesthetic  Tests.  Cut  out  of  wood,  metal  or  card¬ 
board  designs  into  which  a  pencil  point  will  just  easily  fit. 
The  designs  may  be  geometrical  figures,  e.g.,  triangles,  squares, 
oblong  figures,  circles,  ellipses,  etc.,  or  they  may  be  con¬ 
tinuous  line  letters  like  ‘S,’  ‘Z,’  'O,’  ‘M,’  or  ‘V.’  We  have 
used  in  the  Chicago  Laboratory  a  figure  like  the  maze  of  the 
comparative  psychologists,  but  other  purposes  were  primarily 
in  view  and  for  untrained  observers  simpler  figures  are  better. 

With  eyes  closed  or  screened  the  subject  traces  the  figures 
with  a  pencil  in  the  slot,  the  operator  putting  the  pencil  at  the 
start  at  one  or  other  extremity  of  the  figure.  The  tracing  may 
be  done  one  or  more  times  depending  on  the  complexity  of 
the  figure.  Then  the  subject  is  given  a  blank  sheet  of  paper 
in  place  of  the  pattern  and  on  this  he  is  to  report  the  design 
as  he  remembers  it.  His  introspections  are  then  asked.  Half 
a  dozen  tests  with  different  designs  are  sufficient. 


96 


JAMES  R.  AN  CELL. 


An  interesting  variation  of  the  test,  often  resulting,  as  does 
the  original,  in  throwing  more  light  on  visual  than  on  kin- 
aesthetic  imagery,  consists  in  having  the  subject  attempt  to 
reproduce  the  figure  as  it  would  appear  if  turned  about  through 
45°)  90°,  or  270°.  We  have  gotten  many  striking  results, 
too,  from  attempting  either  to  interpret  or  to  reproduce  figures 
traced  in  unusual  positions,  e.g.,  behind  the  back  or  above 
the  head. 

A  simpler  test,  but  on  the  whole  less  successful,  is  the 
familiar  estimation  of  linear  magnitudes.  The  subject  sits 
facing  a  table  on  which  is  a  horizontal  wooden  or  metal  rod 
supported  by  clamps  attached  to  upright  rods.  Two  stops 
are  attached  to  the  horizontal  bar  at  a  convenient  distance 
apart,  say  25  centimeters.  The  index  finger  of  either  hand 
measures  off  the  distance  between  the  stops  by  sliding  along 
the  bar.  The  second  stop  is  then  removed  and  the  subject 
attempts  to  measure  off  the  original  distance.  The  eyes 
must  be  closed  or  averted.  If  short  distances  are  used,  the 
finger  may  move  freely  in  the  air  between  stops  which  must 
be  higher  for  this  purpose.  The  object  of  this  procedure 
is  to  eliminate  the  contact  sensations.  Introspections  are  then 
recorded. 

K.  Taste  and  Smell.  In  the  case  of  olfactory  and  gustatory 
imagery  the  author  is  disposed  to  recommend  going  beyond 
the  questionary  only  when  the  results  from  that  are  negative 
or  highly  ambiguous,  or  when  a  complete  census  on  distribu¬ 
tion  is  desired.  The  difficulty  of  distinguishing  between 
sensations  and  images  is  similar  to  the  difficulty  with  organic 
imagery  and  perhaps  quite  as  serious.  We  have  however  in 
the  case  of  smell,  at  least,  available  tests  which  may  assist 
by  stimulating  introspection. 

One  of  Miss  Gamble’s  tests  may  serve  to  meet  the  olfactory 
case.  A  series  of  ten  odorous  substances  is  prepared  in 
shallow  wide-mouthed  bottles,  with  glass  stoppers.^  The 
subject  sitting  blindfolded  takes  the  bottles  in  the  order 

*  The  following  list  is  easily  secured  and  will  serve  the  purpose.  The  material  in 
any  psychological  laboratory  will  afford  other  equally  good  groups.  Anise,  benzoin, 
bergamot,  cassia,  cloves,  camphor,  creosote,  musk,  peppermint,  sandalwood. 


MENTAL  IMAGERY. 


97 


in  which  they  are  presented,  removes  the  cork,  inhales  once 
and  replacing  the  stopper,  turns  to  the  next  bottle.  After 
the  series  has  been  twice  thus  presented,  the  subject  is  given 
the  bottles  in  disarranged  order  and  asked  to  arrange  them  as 
first  experienced.  The  test  can  be  repeated  several  times  with 
the  same  materials  by  changing  the  order  of  the  stimuli. 

If  olfactory  imagery  is  available,  it  is  reasonably  certain 
to  appear  under  conditions  such  as  these.  The  best  statistics 
make  it  seem  probable  that  such  imagery  is  relatively  rare. 
This  conclusion  is  at  variance  with  the  outcome  of  many 
questionary  investigations.  I  have  frequently,  when  using 
the  questionary,  received  affirmative  answers,  as  have  other 
investigators,  to  the  inquiries  about  such  images.  I  am  dis¬ 
posed  to  attribute  the  discrepancy  to  a  failure  on  the  part 
of  more  naif  observers  to  discriminate  between  pure 
olfactory  images  and  mental  states  which  are  either  illusory 
sensations  or  fusions  of  peripheral  with  centrally  aroused 
factors.  The  more  careful  experimentation  tends  to  render 
subjects  more  sensitive  to  this  distinction  and  more  capable 
of  avoiding  the  possible  confusion  involved. 

No  experimental  technique  seems  to  the  author  success¬ 
ful  in  so  controlling  the  glandular  and  muscular  activities  of 
the  mouth  as  to  make  certain  that  sensations  and  images  of 
taste  are  kept  apart.  The  ordinary  laboratory  forms  of  stim¬ 
ulation  in  connection  with  sensory  discrimination,  for  exam¬ 
ple,  aggravate  rather  than  help  this  difficulty.  At  present, 
therefore,  the  writer  is  not  prepared  to  urge  any  tests  applic¬ 
able  in  a  general  way  as  being  materially  better  than  the 
results  from  the  questionary,  uncertain  and  unsatisfactory 
as  these  are. 

L.  Organic  Tests.  Owing  to  the  serious  difficulty  of  dis¬ 
tinguishing  organic  sensation  from  organic  imagery  it  does 
not  seem  profitable  at  the  present  time  to  go  beyond  the 
inquiry  of  the  questionary,  or  the  possibilities  of  ordinary 
introspections. 


98 


JAMES  R.  ANGELL. 


DIVISION  III. 

M.  Reasoning  Tests.  A  few  tests  on  reasoning  processes 
ought  to  be  included  in  any  diagnostic  series,  not  only  for 
completeness  in  a  program  aimed  at  determining  the  dis¬ 
tribution  of  imagery,  but  also  because  they  serve  to  bring 
out  under  quite  natural  conditions  forms  of  imagery  essen¬ 
tial  to  the  thought  processes  of  the  subject. 

Among  the  most  practicable  are  simple  problems  in  arith¬ 
metical  computation.  For  instance,  the  experimenter  may 
dictate  two-place  numbers,  to  be  added  or  subtracted  men¬ 
tally.  Three,  four  and  five  place  numbers  may  be  written 
down  and  the  arithmetical  operations  carried  on  while  look¬ 
ing  at  the  paper,  but  without  the  assistance  of  pen  or  pencil. 
Introspections  are  asked  for  after  the  subject  completes  and 
announces  the  result  of  his  work.^ 

To  test  the  geometrical  processes  the  problem  of  the  cube 
mentioned  on  page  76  may  be  used  or  one  of  this  kind :  The 
subject  is  told  to  think  of  a  square;  if  a  line  is  made  joining 
a  pair  of  diagonally  opposite  corners,  what  shapes  have  the 
resulting  figures?  If  the  other  two  corners  are  similarly 
joined,  what  shapes  have  the  resulting  figures  and  how  many 
are  there?  Are  they  alike  in  shape  and  size?  ‘How  do  you 
know?’ 

Simple  problems  may  be  selected  from  any  range  of  prac¬ 
tical,  political,  or  scientific  interest,  the  only  essential  con¬ 
ditions  are  that  the  question  shall  be  lucid  and  the  answer 
within  the  capacity  of  the  subject  to  reach.  For  this  purpose 
a  problem  so  difficult  as  simply  to  baffle  attack  is  futile. 

Something  of  this  kind  may  serve  as  a  practical  problem : 
What  route  would  you  take  and  how  would  you  go  about 
making  arrangements,  if  you  were  to  travel  from  your  home 
to  Siberia?  Give  the  steps  in  as  much  detail  as  possible. 
Many  other  more  immediately  personal  problems  will  sug¬ 
gest  themselves  and  may  profitably  be  used. 

Problems  dealing  with  concrete  ethical  situations  may 

1  Dr.  Fernald  has  tried  having  the  computation  carried  on  in  terms  of  the  Roman 
alphai)ct  numerals,  but  without  eliciting  any  forms  of  imagery  not  otherwise  accessible. 


MENTAL  IMAGERY. 


99 


bring  out  interesting  results,  although  the  introspection 
required  is  rather  too  difficult  for  untrained  subjects.  Such 
questions  may  be  illustrated  by  the  old  ethical  problem 
whether  it  is  ever  right  to  lie.  In  the  case  of  a  dying  man  who 
cannot  possibly  recover,  is  it  not  justifiable  to  lessen  the  pain 
of  his  final  hours  by  concealing  from  him  the  seriousness  of 
his  condition?  Questions  of  this  type  and  problems  dealing 
with  relatively  abstract  relations,  may  bring  out  interesting 
evidence  concerning  the  conceptual  imagery  employed.  It 
may  be  mentioned  in  this  connection  that  the  recent  studies 
of  the  process  of  judging,  afford  a  large  range  of  tests  in  which 
the  analysis  of  imagery  may  be  carried  out.^ 

The  experimenter  ought  to  be  especially  alive  in  tests  of 
this  general  variety  to  the  presence  of  symbolic  motor-imag¬ 
ery,  and  enough  non-mathematical  problems  should  be  given 
to  make  sure  whether  or  not  one  has  this  kind  of  imagery  in 
use.  We  bar  mathematical  problems  because  vocal-motor, 
or  hand-motor  imagery  referring  directly  to  numbers,  is  likely 
to  be  used  in  such  cases. 

DIVISION  IV. 

N.  Voluntary  Control  Tests.  Writing  affords  a  very  easy 
and  effective  means  of  access  to  imagery  as  employed  in  the 
control  of  voluntary  movements.  Like  spelling  it  Is  In  part 
a  memory  test,  but  in  the  forms  to  be  mentioned  here  It  is 
primarily  a  test  on  imagery  In  its  relations  to  voluntary 
action,  and  it  furnishes,  together  with  the  tests  on  spelling 
and  reading,  a  transition  from  experiments  on  mere  memory  to 
those  concerned  with  the  analysis  of  voluntary  action. 
[Spelling  and  reading  have  been  treated  under  memory.] 

The  subject  may  be  asked  to  write  either  from  oral  dicta¬ 
tion  or  from  the  printed  copy.  His  introspection  may  then 
be  obtained  and  the  results  compared  with  a  repetition  of  the 
test  in  which  fresh  material  Is  used.  A  paragraph  containing 
a  hundred  words  will  serve  the  purpose.  It  is  well  to  select 
one  in  which  the  vocabulary  is  not  too  familiar  and  common- 

^  Cf.  Titchener,  Experimental  Psychology  of  Thought  Process,  New  York,  1909. 


lOO 


JAMES  R.  ANGELL. 


place.  Passages  from  text-books  on  philosophy  and  psy¬ 
chology  fill  the  bill  admirably  for  ordinary  subjects.  In  at 
least  one  set  of  tests  the  material  written  should  be  something 
known  by  heart,  a  verse  perhaps.  The  writing  begins  at  a 
given  signal  and  on  completion  introspections  are  at  once 
asked. 

Writing  the  letters  of  the  words  backwards  [the  words  being 
spelled  either  forward  or  backward]  from  oral  dictation, 
writing  every  other  letter  of  the  word,  writing  left-handed, 
writing  upside-down,  and  looking-glass  writing,  all  are  excel¬ 
lent  devices  for  throwing  imagery  into  the  foreground,  and 
all  but  the  two  last  are  done  with  sufficient  readiness  by  most 
subjects.  Full  introspections  are  in  every  case  required. 

The  entire  series  selected  may  then  be  repeated  with  the 
eyes  closed.  This  is  often  a  strikingly  useful  variation  of 
the  test. 

We  have  found  it  possible  to  introduce  the  distraction 
methods  quite  successfully  into  the  test.  For  auditory  dis¬ 
traction  one  may  listen  to  a  metronome,  for  motor  distrac¬ 
tion  one  may  repeat  some  well-known  verse,  either  aloud  or 
under  the  breath,  or  one  may  count  rapidly.  For  visual  dis¬ 
traction  one  may  let  the  eyes  follow  the  contour  of  some  con¬ 
ventional  pattern,  or  trace  the  lines  of  overlapping  spirals. 
(The  difficulties  in  securing  satisfactory  distractions  have 
already  been  mentioned.)  The  procedure  in  the  case  of  audi¬ 
tory-motor  distraction  may  suffice  to  make  clear  the  method. 
The  subject  with  eyes  closed  is  told  upon  receiving  a  signal  to 
begin  writing  the  first  verse  of ‘America;’ while  he  writes,  he 
is  to  sound  the  vowel  ‘a.’ 

A  great  many  experiments  have  been  conducted  in  recent 
years,  to  determine  the  psychological  processes  controlling 
voluntary  action,  and  especially  with  a  view  to  determining 
the  part  played  by  imagery.  If  the  tests  on  writing  and  spell¬ 
ing  are  used,  especially  in  the  more  infrequent  forms  like 
writing  with  the  left  hand,  and  like  spelling  backward,  there 
need  be  very  few  additions,  at  least  so  far  as  concerns  ascer¬ 
taining  the  kinds  of  imagery  which  can  be  commanded.  If 
exhaustive  tests  on  normal  distribution  are  desired,  we  must 


MENTAL  IMAGERY. 


lOI 


add  to  the  list  tests  involving  new  coordinations,  or  at  all 
events,  radically  new  combinations  of  old  coordinations. 
Learning  (i)  to  move  the  ears,  to  move  the  scalp  over  the 
crown,  to  move  the  toes  independently  of  one  another,  and 
(2)  learning  to  finger  a  musical  instrument  may  illustrate 
the  two  main  types  of  cases. ^ 

Tests  of  this  character  require  so  extended  a  period  of  work 
as  to  render  them  rather  inappropriate  for  detailed  mention 
in  context  with  the  other  tests  of  this  group.  Reference  is 
made  below  to  one  or  two  studies  on  the  learning  of  such 
acts.  An  investigation  of  one  form  of  the  process  is  now 
nearing  completion  in  the  Chicago  Laboratory, ^ 

Part  III.  Gradation  of  Images. 

Most  of  the  investigations  hitherto  conducted  have  under¬ 
taken  to  offer  some  quantifying  statements  with  reference  to 
the  vividness,  stability,  ease  of  attaining  the  images,  and  so 
on.  In  the  opinion  of  the  present  writer  the  gradations  which 
have  often  been  employed  in  such  scaling  of  the  qualities  of  im¬ 
agery,  are  too  refined  to  be  successfully  employed  by  the  ordin¬ 
ary  observer.  For  instance,  writers  on  imagery  who  report 
upon  grades  of  intensity  or  grades  of  vividness®  have  often 
employed  six  or  more  distinctions  in  accordance  with  which 
they  have  asked  their  subjects  to  make  their  reports. 

The  effort  to  subject  this  matter  to  a  satisfactory  series  of 
control  tests  proved  impracticable  for  the  following  reasons. 

1  The  case  of  learning  to  move  the  ears  and  learning  to  move  the  toes  independently 
of  one  another  differ  in  that  one  involves  gaining  control  over  a  wholly  unused  muscle, 
the  other  involves  separating  muscular  innervations  which  have  always  occurred 
together. 

^  Bair,  Acquirement  of  Voluntary  Control,  Psychol.  Rev.,  vol.  viii,  1901,.  p.  474. 
Book,  Psychology  of  Skill,  University  of  Montana  Studies,  vol.  i,  1908. 

®  The  author  does  not  feel  under  obligation  to  enter  upon  the  controversy  concern¬ 
ing  the  genuineness  of  the  intensive  attribute  as  applied  to  imagery,  nor  the  differen¬ 
tiation  of  intensity  from  vividness  and  of  both  from  clearness.  If  vividness  or  inten¬ 
sity  are  either  of  them  genuine  characteristics  of  the  image  process,  gradation  is  at 
least  theoretically  possible  and  it  becomes  proper  for  a  report  of  this  kind  to  make 
recommendations  concerning  it.  That  ordinary  observers  are  able  to  make  distinc¬ 
tions  which  seem  to  them  natural  and  easy,  when  asked  to  grade  their  imagery  in  this 
way,  affords  a  strong  prima  facie  case  for  the  genuineness  of  the  distinction  reported. 


102 


JAMES  R.  AN  CELL. 


If  a  series  of  images  could  be  secured  on  a  number  of  succes¬ 
sive  occasions,  with  precisely  the  same  degree  of  vividness, 
it  would  be  possible  by  tabulating  the  classifications  made 
by  the  subjects,  to  ascertain  with  what  degree  of  nicety  they 
could  consistently  grade  the  experiences.  But  evidently  we 
can  secure  no  such  guaranty  of  the  actual  similarity  in  vivid¬ 
ness  of  the  imagery  on  these  successive  occasions.  Any  con¬ 
sistency  which  the  subject  may  evince  becomes  therefore 
ambiguous  and  inconclusive.  On  the  other  hand  a  failure  to 
classify  the  images  in  the  same  way  on  different  occasions  is 
no  guaranty  at  all  that  the  classifications  are  untrustworthy. 

The  author’s  observations  extending  over  a  number  of 
years  and  including  in  their  range  a  large  number  of  individu¬ 
als  leads  him  to  believe  that  occasionally  subjects  are  able  to 
grade  their  images  on  the  scale  of  eight  with  entire  confidence 
and  with  practical  consistency.  The  difficulty  which  is  most 
likely  to  be  troublesome  in  the  case  of  such  observers  is  the 
reduction  to  a  common  scale  of  imagery  belonging  to  two 
different  sense  departments  like  vision  and  audition.  The 
maximal  degree  of  vividness  in  the  one  case  may  seem  very 
different  from  the  maximal  degree  in  the  other,  and  still  the 
subject  may  feel  indisposed  to  call  the  weaker  group  of  images 
in  any  sense  faint  or  indistinct.  Our  statistics  do  not  at  pres¬ 
ent  in  the  author’s  judgment  afford  us  adequate  information 
as  to  whether  the  scale  of  intensities  for  the  different  forms  of 
imagery  is  of  equal  extent,  much  less  whether  the  threshold 
of  noticeable  differences  in  it  is  any  wise  homogeneous. 
Under  these  circumstances  one  must  regard  any  estimates  of 
gradation  as  being  merely  rough  approximations. 

For  the  reasons  just  discussed,  as  well  as  for  another  highly 
important  reason  next  to  be  mentioned,  the  author  has  come 
to  believe  that  three  gradations  are  as  much  as  can  be  profit¬ 
ably  and  safely  recognized  in  the  presentation  of  statistics  on 
imagery.  The  additional  reason  which  has  had  great  weight 
with  the  author  has  been  the  testimony  of  several  psycholo¬ 
gists  of  distinction  and  wide  experience  that  they  themselves 
found  it  entirely  impossible  to  make  so  many  gradations  as 
the  questionary  commonly  demands.  The  procedure  here 


MENTAL  IMAGERY. 


103 


recommended  would  in  the  case  of  vividness,  for  example, 
recognize  three  divisions  which  may  be  called  very  vivid, 
moderately  vivid,  and  faint.  Subjects  who  feel  the  necessity 
for  intermediate  grades  can  be  supplied  with  these  by  the 
use  of  plus  and  minus  signs.  Thus,  the  gradation  faint  might 
be  modified  to  provide  two  more  classes  by  adding  a  plus 
sign  for  images  which  are  slightly  above  this  level  and  a 
minus  sign  for  those  which  are  below.  A  similar  treatment 
of  each  of  the  other  main  divisions  would  give  nine  differenti¬ 
ations,  which  is  fully  adequate  to  care  for  any  case  that  the 
author  has  ever  encountered.  ^ 

Even  after  we  have  agreed  upon  the  number  of  gradations 
to  be  recognized,  the  problem  still  remains  in  dealing  with 
individual  subjects,  how  we  are  to  instruct  them  in  the  use 
of  such  standards,  which  are  in  the  nature  of  the  case  rather 
arbitrary  and  altogether  subjective.  On  this  point  the  author 
has  no  dogmatic  advice  to  offer.  In  his  own  experience  two 
types  of  procedure  have  seemed  practicable.  In  one,  the 
subject  is  given  no  definite  advice  or  suggestions,  but  is  sim¬ 
ply  advised  to  wait  until  he  has  inspected  twenty  or  thirty 
images  before  beginning  his  gradations.  He  is,  moreover, 
allowed  to  revise  his  gradations  if  they  appear  to  him  incon¬ 
sistent  with  one  another.  For  example,  a  subject  may  start 
out  classifying  a  given  image  as  very  intense,  only  to  find 
toward  the  end  of  his  observations  that  another  image  is 
noticeably  more  intense.  In  this  case  he  naturally  wishes  to 
scale  down  all  the  other  statements  which  he  had  made  on 
the  basis  of  his  first  relatively  vivid  image.  The  second  pro¬ 
cedure  involves  attempting  to  give  the  subject  suggestions  in 
which  his  attention  is  called  to  the  possibility,  for  example, 
that  the  most  vivid  image  might  approach  a  perceptual  exper¬ 
ience  in  its  character.  It  is  also  suggested  that  the  faintest 
image  would  be  almost  impossible  to  detect.  Suggestions  of 
this  sort  are  sure  in  the  case  of  some  subjects  to  be  helpful, 
but  others  are  not  materially  assisted  and  in  a  few  cases  the 
suggestions  have  proved  confusing  rather  than  otherwise. 
In  the  view  of  the  writer  these  difficulties  indicate  simply 
that  gradations  of  the  kind  mentioned  are  of  very  problem- 


104 


JAMES  R.  AN  CELL. 


atic  significance  when  gathered  from  untrained  observers 
without  the  possibility  of  some  measure  of  verification. 

Gradations  of  stability  would  likewise  be  made  on  the 
basis  of  three  distinctions;  first,  very  stable,  approaching 
perception  in  fixity;  second,  moderately  stable;  third,  very 
fleeting.  Here  again  by  a  system  of  plus  and  minus  symbols 
the  demand  for  a  finer  classification  may  be  met  if  it  arises. 

It  need  not  be  argued  that  stability  as  a  category  of  mental 
imagery  is  primarily  applicable  to  the  space  mediating  sen¬ 
sations.  Images  of  sound  are  often  In  the  nature  of  the  case 
momentary  and  fleeting.  In  their  case  revivability  would 
serve  the  same  function  in  large  part  which  stability  serves 
In  the  case  of  the  visual  imagery.  In  a  similar  way  olfactory 
images,  when  they  can  be  gotten,  are  likely  to  be  transitory, 
even  though  they  may  be  recalled  repeatedly. 

Almost  all  subjects  are  able  to  report  with  confidence  on 
the  ease  or  difficulty  with  which  they  can  command  imagery. 
The  gradations  used  may  be  Very  easy,’  ‘moderately  easy,’ 
‘difficult.’  The  plus  and  minus  system  affords  adequate  recog¬ 
nition  of  the  differences  met  with  in  practice. 

In  the  case  of  memory  tests  a  grading  of  accuracy  is  Instruc¬ 
tive  and  the  matter  of  detail  may  always  be  advantageously 
graded  if  gradation  of  any  kind  is  to  be  attempted. 

In  the  judgment  of  the  author  as  was  intimated  a  few  lines 
above,  the  entire  problem  of  gradation  may  well  wait  upon  a 
more  complete  investigation  of  the  qualitative  peculiarities 
of  imagery  before  attempting  to  define  a  definite  line  of  pro¬ 
cedure.  At  the  present  time  it  seems  more  than  doubtful 
whether  we  can  secure  standards  for  this  purpose  so  intel¬ 
ligible  and  so  readily  applicable  as  to  enable  us  to  secure  uni¬ 
formity  among  different  investigators. 

The  author  undertakes  to  offer  no  exhaustive  bibliography 
of  the  subject.  The  references  which  have  been  cited  in  the 
body  of  the  text  are  here  brought  together  for  convenience, 
and  to  them  are  added  a  number  of  other  titles.  The  list 
contains  the  works  which  the  author  has  found  most  directly 
useful,  and  which  he  believes  present  a  just  and  essentially 
adequate  record  of  the  progress  in  the  study  of  Imagery  since 
Galton’s  work. 


MENTAL  IMAGERY. 


lOS 


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viii,  p.  474. 

Baldwin,  J.  M.  Internal  Speech  and  Song.  Phil.  Rev.,  1893,  vol.  ii,  p.  385. 

Ballet,  G.  Le  Langage  Interieure,  Paris,  1886. 

Bawden,  H.  H.  Study  of  Lapses,  Psy.  Rev.  Monog.,  1900,  vol.  iii,  no.  14. 

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Brown,  C.  E.  Psychology  of  Arithmetical  Processes,  Amer.  Jour.  Psy., 
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p.  161. 

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1909,  vol.  vi,  p.  223. 

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Frankl,  E.  Ueber  Vorstellungselemente  und  Aufmerksamkeit,  Ausghmg, 
1905. 


io6 


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Fraser,  A.  Visualization  as  a  Chief  Source  of  the  Philosophy  of  Hob¬ 
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French,  F.  C.  Mental  Imagery  of  Students,  Psy.  Rev.,  1902,  vol.  ix,  p. 

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tistics  of  Mental  Imagery,  Mind,  1880,  vol.  v,  p.  301. 

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vol.  xxxiii,  p.  597. 

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Keraval,  P.  Le  langage  ecrit,  Paris,  1897. 

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1895  vol.  i,  p.  73. 

Kries,  J.  V.  Ueber  das  absolute  Gehor,  Zeit.  f.  Psychol.,  1892,  vol.  iii, 
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P-  534. 


APPENDIX 


After  the  foregoing  report  was  in  type,  Professor  L.  J. 
Martin  presented  before  the  American  Psychological  Asso¬ 
ciation,  at  its  annual  meeting  held  at  Minneapolis  during  the 
last  week  of  December  1910,  an  interesting  account  of  some 
experiments  on  the  projection  of  visual  images. 

Professor  Martin  put  before  her  subjects  common  articles 
such  as  books,  ink  bottles  and  water  glasses.  They  were  then 
instructed  to  attempt  to  form  and  project  a  visual  image  of 
the  object  which  was  to  appear  just  beside  the  perceptual 
original.  The  image  and  the  percept  were  then  compared. 
A  considerable  number  of  her  subjects  were  reported  as  able 
to  do  this  satisfactorily. 

The  tests  in  the  present  paper  [Pt.  II,  Div.  HE]  dealing 
with  the  description  of  objects  and  pictures  resemble  Pro¬ 
fessor  Martin’s  tests  in  some  particulars  and  proved  extremely 
illuminating,  as  has  already  been  stated,  when  a  comparison 
was  made  at  the  end  of  the  test  between  the  image  and  its 
perceptual  original.  Such  comparison  is  obviously  analogous, 
though  by  no  means  identical,  with  her  procedure  in  re¬ 
quiring  a  direct  comparison  of  the  image  with  the  object,  the 
two  being  ostensibly  present  simultaneously.  Her  nTethod 
certainly  deserves  further  study.  But  it  is  clearly  exposed 
to  certain  introspective  inaccuracies  which  would  need  to  be 
carefully  safe-guarded,  if  the  test  were  employed  upon  inex¬ 
perienced  observers.  Our  own  results  indicated  far  less  cap¬ 
acity  of  projection  in  our  subjects  than  in  hers. 


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